41Skin and Soft-Tissue Lesions

Bradley N. Delman, Jane L. Weissman,and Peter M. Som

INTRODUCTIONSKIN AND SUBCUTANEOUS LESIONS

ScarHypertrophic ScarKeloidEpidermoid Cyst (Sebaceous Cyst)PilomatrixomaBasal Cell CarcinomaSquamous Cell Carcinoma of the SkinMelanomaMerkel Cell TumorSkin MetastasisSubcutaneous Fat Necrosis of the NewbornSclerema NeonatorumPlexiform Neurofibroma and Skin

NeurofibromasSilicon AugmentationAlloderm AugmentationForeign Bodies

FAT-CONTAINING LESIONSOrdinary LipomaInfiltrative (Intramuscular) LipomaMadelung’s DiseaseLiposarcoma

INTERSTITIAL LESIONSFibrosarcoma

Benign Fibrous Lesions (Fibromatoses)Desmoid TumorCongenital Fibromatosis (Generalized and

Localized)Nodular Fasciitis (Pseudotumor of the Skin)

Proliferative FasciitisNecrotizing Fasciitis

MUSCLE-RELATED LESIONSLevator Claviculae MuscleDenervation Atrophy

Muscle HypertrophyFibromatosis Colli (Sternomastoid or

Sternocleidomastoid Tumor)Muscular TorticollisMyositisMyositis OssificansMuscular DystrophiesMyotonic DystrophyRhabdomyosarcomaMetastasis to Muscle

THE STYLOHYOID SYNDROMESEagle’s SyndromeStyloid CarotodyniaHyoid Fasciitis

BLOOD VESSELS AND VASCULAR VARIATIONSVeins

Asymmetry of the Internal Jugular VeinsMultiple Jugular VeinsPhlebectasiaThrombosisPseudocollateral and Collateral VeinsCondylar Vein

ArteriesMedial Deviation of the Carotid ArteryAberrant Retroesophageal Right Subclavian

ArteryThrombosis and DissectionAneurysm

HemangiomaHemangiopericytoma

PERIPHERAL NERVE SHEATH TUMORSPHARYNGOESOPHAGEAL LESIONS

Zenker’s DiverticulumDilated/Obstructed Cervical Esophagus

41-1

INTRODUCTION

There are a variety of skin and soft-tissue lesions in thehead and neck with manifestations that can be seen on CTand MR imaging. Although overall there are a large numberof such lesions, this chapter will address only some of themore common ones and discuss pertinent differentialdiagnoses.

SKIN AND SUBCUTANEOUS LESIONS

The skin (integument, cutis) is largely ignored on CT andMR imaging. In this section, the skin (epidermis, dermis,and the skin appendages including the pilosebaceous units[hair, sebaceous and apocrine glands, and associated smoothmuscle fascicles]) and the immediate subcutaneous tissuesare considered.

Diffuse thickening of the skin is most commonly seen inedematous and inflammatory conditions. However, diffuseskin thickening can also be seen after irradiation or, rarely,with tumor infiltration. Almost always, there is associatedthickening of the subcutaneous fat and injection of this fatwith a rete-type pattern of soft tissue representing dilatedlymphatic and vascular capillaries and venules. In addition,after trauma there can be subcutaneous hemorrhage andhematoma (Figs. 41-1 to 41-3). When clinical and imagingdistinction between these entities is difficult, serial imagingmay offer increased specificity: hematomas tend to showevolution and resolution; there is relative stability orimprovement with radiation changes; and tumors may

progress to variable degrees, depending on their histologyand aggressiveness. Phlegmon, a collection of watery fluidwithin the interstitial tissues and spaces of the neck, isusually associated with an acute suppurative inflammation.

FIGURE 41-2 Axial contrast-enhanced CT scan shows markedthickening of the skin and subcutaneous tissues of the left posterior neck,all secondary to a cellulitis from a skin infection.

FIGURE 41-1 Axial contrast-enhanced CT scan (A) shows mild thickening of the skin in the left neck, markedthickening of the subcutaneous fat with prominence of dilated lymphatic and vascular capillaries and venules, andthickening of the platysma (arrowheads), all secondary to an acute left submandibular sialadenitis (S ). Axialcontrast-enhanced CT scan (B) on another patient shows the changes of cellulitis in the right submandibular triangle.In addition, there is an abscess with an enhancing rim. The abscess displaces the submandibular gland posteriorly.

41-2 NECK

Cellulitis can be seen with simple phlegmon or abscess, withan abscess distinguished from phlegmon by the presence ofan enhancing rim (Fig. 41-1B). Further examples of thesechanges can be seen throughout other sections in this book.

Scar

Scar formation occurs whenever there has been anulceration or laceration of the skin. The type of scar oftenreflects the pattern of healing; thus, a scar may be flat,hypertrophic, or atrophic. It may also be firm or, as a resultof collagen proliferation, hard. The skin appendages andskin lines are usually lost within the scar bed. On imaging,scars may vary significantly in appearance. The routine flatscar may not be clearly seen, so the only clue to the surgicalline may be an infolding of the skin. Conversely, there maybe an obvious skin thickening, often in conjunction withsubcutaneous scar extending almost as deeply as the muscleline (Fig. 41-4).

Hypertrophic Scar

A hypertrophic scar usually develops when woundmargins are placed under tension. The clinical featuresdistinguishing hypertrophic scars from keloids include theobservation that hypertrophic scars remain confined to theoriginal scar line, and with time they tend to flatten out orregress spontaneously. Histologically, they lack hyalinizedcollagen bundles, and they contain little or no mucinousground substance. Fibroblasts and foreign body granulomasare also common. Like keloids, these lesions have a higherwater content than normal scar and skin, although the watercontent tends to diminish as the scars age.1 While distinctionfrom keloids may prove difficult by CT, studies on resectedtissue have shown that the T1-weighted signal intensity ofhypertrophic scar tends to reach normal levels within 1 to 2years, unlike keloid, in which the T1-weighted signalintensity may take 10 years to normalize.1 Treatment of

hypertrophic scars is similar to that of keloids, but onlyabout 10% of hypertrophic scars recur.2

Keloid

Keloids are benign overgrowths of dermal scar tissue thatusually develop after local trauma, although sometimesthere has been no identifiable insult. They are more commonin dark-skinned individuals and in people with blood groupA, and a family history may be present. Their growth may beaccelerated by pregnancy and puberty. Keloids are slightlymore common in women, and most arise in people between10 and 30 years of age, probably due to the higher incidenceof trauma and acne in this age group.2

About 70% of postsurgical keloids develop within 6months of surgery, but up to 17% may appear one yearor more after surgery. Most keloids are significantonly because of their cosmetic nature, although somemay be associated with pruritis, pain, and/or paresthesias.Despite the fact that their borders are usually welldemarcated, they tend to be irregular in outline. Keloidsusually grow outward from the original scar line andextend into adjacent tissues. On imaging, they are bulkysoft-tissue masses that project away from the skin line(Fig. 41-5). There may be subcutaneous infiltration, oftenrelated to prior surgery rather than directly to the keloid.Histologically, keloids are composed of thick, glassy,eosinophilic or hyalinized bundles of collagen, oftenassociated with abundant mucinous ground substance. Thebulky overgrowth of tissue may reflect an attempt toduplicate the tensile strength of normal skin within thisdisordered collagen-containing scar tissue. Treatment of

FIGURE 41-3 Axial CT scan shows a soft-tissue density in thesubcutaneous tissues of the left facial area representing hematoma. Thereare also edematous changes in the adjacent soft tissues due to edema. Thereis dense fluid in the left maxillary sinus. This patient fell and developed ahematoma and edema in the left face with hemorrhage in the left antrum.

FIGURE 41-4 Axial contrast-enhanced CT scan on a patient who hada left radical neck dissection. A surgical clip is seen in the left neck. Notethe thin scar line (arrow) and the relatively small amount of fibrosis withinthe subcutaneous tissues. Minimal edematous change is seen in theadjacent subcutaneous tissues.

Chapter 41 Skin and Soft-Tissue Lesions 41-3

keloids includes excision, irradiation, and injection withcorticosteroids, although up to 63% may recur aftertreatment.2

Epidermoid Cyst (Sebaceous Cyst)

The epidermoid cyst—the commonly used term seba-ceous cyst is a misnomer—is the result of the proliferation ofsurface epidermoid cells within the dermis. The lining ofmany nontraumatic cysts is believed to be derived from thefollicular infundibulum, as these cysts commonly developfrom the occlusion of pilosebaceous follicles. Less commoncauses include the implantation of epidermal cells into thedermis secondary to a penetrating injury and the trapping ofepidermal cells along the lines of embryonal fusion planes.These cysts are rare in children but common in adults, andpatients with basal cell nevoid syndrome may havenumerous lesions. On imaging, these cysts are ovoid inshape, with a noninfiltrating rim. The superficial margin ofthe cyst usually touches the deep skin line, and the cyst isfilled with mucoid attenuation material and scattereddystrophic calcifications (Fig. 41-6).

These cysts are usually slowly growing, painless massesthat elevate the skin and often have a central punctum thatrepresents the plugged orifice of the pilosebaceous follicle.The cysts are filled with cheesy, keratinous yellow-whitematerial. They may become infected; uncommonly, theymay rupture, causing a foreign body reaction.3

The differential diagnosis includes pilar cyst of thescalp and face and steatocyst simplex.4 Steatocysts areoften confused with epidermoid cysts, although steatocysts

can be distinguished by the yellow, oily fluid that theycontain.

Pilomatrixoma

Pilomatrixoma, or calcifying epithelioma of Malherbe, isan uncommon benign neoplasm of hair follicle origin. Theseneoplasms favor the hair-bearing areas, and approximatelyhalf of the reported tumors have been in the head and neckregion. The majority of cases have been reported in patientsin their first two decades of life; however, there is a secondpeak of occurrence in older patients. Overall, there is afemale predominance.

Histopathologically, there are hair matrix–like basaloidcells and shadow or ghost cells, which have a centralunstained area that represents a shadow of a lost nucleus.Intracellular and stromal calcification is reported in about70% of cases, and tumors with large areas or nests of shadowcells proportionally have increased calcium deposition. Ithas been suggested that osteopontin, a protein markerassociated with bone production, may be produced bymacrophages and play a role in the deposition of calciumphosphate in the shadow cell nests.

The typical patient presents with an asymptomatic,superficial, solitary, firm mass that is located either withinthe dermis or in the subcutaneous fat, with tethering to thedermis. The overlying skin often has a reddish-bluediscoloration. Even though these tumors usually growslowly (months to years), excision is usually recommendedto avoid a foreign body reaction, associated inflammation,and resulting scar formation. Complete surgical excision is

FIGURE 41-5 Axial contrast-enhanced cranial (A) and caudal (B) CT scans show a huge keloid in the rightneck. Although there is some subcutaneous extension along the scar line, the vast majority of the mass is superficialto the skin. A second smaller keloid is present in the left neck (arrowhead in B). Incidentally noted is level I reactiveadenopathy.

41-4 NECK

curative. Multiple tumors account for 2% to 3.5% ofreported cases, and there have been reported rare associa-tions with myotonic muscular dystrophy, Gardner’s syn-drome, sarcoidosis, and skull dysostosis. A rare familialoccurrence not associated with other syndromes has alsobeen reported.5

On CT, the lesion appears as a noninfiltrating mass inthe subcutaneous fat with varying degrees of focal calci-fication. There is no significant enhancement with iodin-ated contrast. The tumor margin cannot be separated fromthe epidermis; hence, the mass appears contiguous withthe overlying skin. There is no extension into the under-lying musculature (Fig. 41-7). Pilomatrixomas have avariable appearance on MR imaging, ranging from inter-mediate to slightly hyperintense on T1-weighted imagesand slightly hypointense to slightly hyperintense on T2-weighted images. One report suggests that bands ofincreased T2-weighted signal intensity seen extendingfrom the periphery of the lesion to its center may represent

basaloid sheets identified histologically.6 No gadoliniumenhancement has been described. On ultrasound, thiswell-defined lesion is typically hyperechoic centrally, witha thin hypoechoic rim; distal shadowing from calcifica-tions is common.7

The differential diagnosis includes sebaceous cyst,foreign body reaction, ossifying hematoma, giant cell tumor,chondroma, dermoid cyst, degenerating fibroxanthoma,metastatic bone formation, and osteoma cutis. The very raremalignant counterpart of the pilomatrixoma is the pilomatrixcarcinoma, which is characterized by vascular and muscleinvasion as well as local recurrence following resection.Distant metastases are uncommon but have been reported.The differential diagnosis of this malignancy includes basalcell carcinoma with matrical differentiation, matricoma, andmetastasis.5 Proliferating trichilemmal tumors, which mayappear similar to invasive pilomatrixomas, are instead likelyto arise from trichilemmal cysts that have been exposed totrauma or inflammation.4

FIGURE 41-6 Axial contrast-enhanced CT (A) scan shows a typicalwell-defined cyst in the subcutaneous tissues of the right posterior neckabutting on the deep surface of the skin. Axial contrast-enhanced CTscans (B and C) on two other patients show cysts in the posterior neck;however, there are scattered calcifications within these cysts. All of thesepatients had epidermoid cysts. Axial contrast-enhanced CT scan (D) onanother patient shows an infected cyst in the left neck. Note theenhanced, thickened posterior border of the cyst. Clinically, pus fromthis sebaceous cyst was evident.

Chapter 41 Skin and Soft-Tissue Lesions 41-5

Basal Cell Carcinoma

Basal cell carcinoma is the most common type of skincarcinoma. It is more common in males and rarely occursin dark-skinned people or Asians. The increased inci-dence in individuals with light hair, light skin, inability totan, and prolonged sun exposure has long implicatedactinic damage in the pathway of basal cell carcinomadevelopment. In addition, patients who have basal cellcarcinoma are three times more likely than the normalpopulation to develop another UV–related malignancy,melanoma.8 Basal cell carcinomas tend to occur in thecentral midface. Prognostically, these tumors tend to bemore aggressive than basal cell tumors at other head andneck sites.2

After tumor site, histologic type is the most importantfactor in determining the prognosis. Overall, basal cellcarcinomas rarely metastasize (0.1%), but tumors withsquamous differentiation and/or an adenoid pattern occur-ring about the orbits have the highest incidence ofmetastasis. Perineural, lymphatic, and vascular-type metas-tasis can occur, and once metastasis has developed, theaverage survival is only 1 to 2 years. Histologic analysisshows that basal cell carcinomas grow into the dermis ascords, strands, and sheets of small basaloid cells; centrilobu-lar necrosis is not uncommon.9 Surgery is the treatment ofchoice.2

On imaging, basal cell carcinomas have a variableappearance, depending on the size of the tumor at the time ofimaging. When small, they are soft-tissue masses in the skinline, usually with deep extension into the subcutaneoustissues (Fig. 41-8). When large, they appear as deeplyinfiltrating soft-tissue masses. Basal cell and squamous cellcarcinomas can be difficult to distinguish by imaging,

although secondary findings such as adenopathy favor thelatter.

Basal cell nevoid syndrome (Gorlin syndrome, Gorlin-Goltz syndrome) is an autosomal dominant disorder inwhich patients develop multiple basal cell carcinomas(especially at a young age), odontogenic keratocysts, palmarand plantar pitting, falx and dural calcifications, and skeletalmalformations. Associations with many other benign andmalignant tumors have also been reported. Other conditionsin which relatively young patients develop basal cellcarcinomas include xeroderma pigmentosum and nevussebaceus.

Squamous Cell Carcinoma of the Skin

Squamous cell carcinoma of the skin commonly occursin the head and neck. These tumors can arise de novo orin preexisting lesions such as actinic keratosis or squa-mous cell carcinoma in situ (Bowen’s disease). There is ahigh incidence of squamous cell carcinomas in patientswith hereditary skin diseases such as oculocutaneousalbinism or xeroderma pigmentosum.2 Men are morecommonly affected than women (2; 1), and most tumorsarise in the sixth and seventh decades of life. Histologi-cally, these are neoplasms of keratinocytes in the surfaceepidermis or in the epithelium of adnexal structures.Tumor typically penetrates the reticular dermis. Theincidence of metastasis varies from 5% to 30%. Mostresearchers believe that the prognosis is not related to thehistologic grade; however, the depth of invasion and theamount of surface area between the tumor and stroma maybe related to the incidence of metastasis. Once squamouscell carcinoma of the skin has metastasized, the prognosisis poor, with 57.3% of patients dead of their diseasewithin 5 years.2

FIGURE 41-7 Axial contrast-enhanced CT scan shows a well-definedcystic-appearing mass with scattered calcifications in the subcutaneous softtissues of the face. There is a broad margin of the mass abutting the deepaspect of the skin. This patient had a pilomatrixoma. Note the imagingsimilarity to a epidermoid cyst (Fig. 41-6).

FIGURE 41-8 Axial contrast-enhanced CT scan shows a mass in theskin line of the left posterior neck. The deep margin is unsharp in someareas. This patient had a basal cell carcinoma.

41-6 NECK

Melanoma

Melanoma is a highly malignant tumor of melanocytesderived from the neural crest. The primary factor associatedwith the development of melanoma is excessive exposure toUV radiation, so patients with benign (melanocytic) nevi,freckles, dysplastic nevi, and a history of three or moresevere sunburns are all at increased risk. Lymphoscintigra-phy has proven useful in defining drainage pathways andsuggesting which nodes are most likely to harbor metastaticdeposits. Approximately one fourth of supraclavicularcutaneous melanomas arise on the neck; the second mostcommon site is behind the scalp (36%); less frequent sitesinclude the face (22%) and ear (14%).10

Numerous studies indicate that females have a betterprognosis than males, possibly due to earlier detection andtreatment. A possible increase in melanoma progression dueto pregnancy and female hormone replacement therapy hasrecently been disproven.11 Factors associated with improvedsurvival include age less than 60 years and thinner lesionswith less invasion.12 The 10-year survival rate has beenreported as high as 70% in males and almost 90% in females,although most studies report an overall 5-year survival rateof about 70%.12, 13 Approximately 15% of patients die fromtheir melanoma, and only 5% of patients with metastaticmelanoma remain recurrence free for the remainder of theirlives.14 Mucosal melanomas are also associated withsignificant morbidity; these are discussed in Chapter 6.

Merkel Cell Tumor

Merkel cell tumor (trabecular carcinoma, cutaneoussmall cell undifferentiated carcinoma, primary neuroendo-crine carcinoma) is an undifferentiated tumor of the skin,which in the elderly may clinically mimic a basal cellcarcinoma. The typical patient is Caucasian and above 50years of age.15 As in melanoma, a neural crest origin issuspected. Approximately 25% of patients also developsquamous cell carcinoma in the same region, eitherseparately or interspersed within the Merkel tumor itself.9

Overall, the incidence correlates with sun exposure, and thehead and neck region may account for two thirds of all cases,although the extremities and buttocks are also frequent sites(Fig. 41-9).16 Patients with B-cell malignancies who haveundergone organ transplantation are also at increased risk.15

The Merkel cell tumor is usually identified as a slowgrowing nodule. The vast majority of patients present withlocalized skin lesions and no nodal disease. However, theseare aggressive tumors and should be treated by wide surgicalexcision. Median survival is 29 months, with evidence thatradiotherapy improves absolute 5-year survival (38% vs.27%).16, 17 Local recurrence occurs in about a third ofpatients, while nodal metastases are seen in 50% andvisceral metastases in 15%.2

Skin Metastasis

Metastasis to the skin has been reported from a numberof primary head and neck tumors, as well as from most

of the common primary neoplasms arising below theclavicles.18–27 In all cases, such metastases carry anassociated dire prognosis. On imaging, the skin linesoft-tissue mass is similar in appearance to a basal cell orsquamous cell carcinoma (Fig. 41-10). Tumor implantationhas also been reported about the tracts of drains placedduring resection of numerous malignancies.

Subcutaneous Fat Necrosis of the Newborn

Subcutaneous fat necrosis of the newborn (SCFN) is acondition affecting full or postterm infants, starting days toweeks after a complicated perinatal period. It is character-ized by the appearance of one or more well-defined,

FIGURE 41-10 Axial contrast-enhanced CT scan shows a mass in theskin and subcutaneous tissues of the left posterior neck. The margins of thelesion are unsharp. This was a rare skin metastasis from a pharyngealsquamous cell carcinoma. Note the postoperative changes in the rightanterior neck from the primary tumor resection.

FIGURE 41-9 Axial CT scan shows a soft-tissue mass in thesubcutaneous tissues of the left face. Portions of the contour of the lesionare unsharp, suggesting focal infiltration. This patient had a Merkel celltumor.

Chapter 41 Skin and Soft-Tissue Lesions 41-7

nonsuppurative, erythematous or violaceous, mobile subcu-taneous masses, often with taut overlying skin. There isusually a history of obstetric manipulation, perinatalasphyxia, meconium aspiration, or maternal disease. Thetypical lesions develop on the shoulders, back, buttocks,thighs, and cheeks. It has been postulated that these lesionsresult from localized tissue hypoxia and mechanicalpressure, which further compromises the local circulation. Ithas also been suggested that thrombocytosis may play a rolein the pathogenesis of adipose tissue necrosis by reducingblood perfusion, leading to relative hypoxia and hypother-mia. The nodules of SCFN may enlarge for several weeks tomonths but then usually involute. Rare local complicationsinclude epidermal atrophy, ulceration, scarring, or infec-tion.28

Pathologically, SCFN is characterized by clusters ofadipocytes, histiocytes, fibroblasts, scant lymphocytes, andnumerous foreign body giant cells. Granulomatous fatnecrosis and calcifications are seen. Hypercalcemia is themost serious complication associated with SCFN; it isbelieved to be caused by an excess production of 1,25-dihydroxyvitamin D by the granulomatous macrophages.Because hypercalcemia may occur anytime from 1 to 6months after the skin lesions first develop, these neonatesshould have calcium levels monitored for at least 6 months.The radiologist should monitor for possible renal complica-tions of hypercalcemia, and renal ultrasonography isrecommended to exclude nephrocalcinosis and nephrolithi-asis. Other clinical associations with hypercalcemia includehypotonia, vomiting, anorexia, irritability, and failure tothrive.29

On CT, the lesions of SCFN appear localized to thesubcutaneous tissues immediately deep to the skin. Thenodules may have minimally infiltrative margins and areasof central low density only slightly higher in attenuationthan that of fat. The nodules may partially obliterate the fatplanes over the superficial margin of an adjacent deepmuscle; however, the muscle itself and the deeper fat planesabout the muscle are normal. There also may be a diffusesubcutaneous fullness with increased attenuation in the fat,without a discrete mass (Fig. 41-11).

Linear or sheet-like areas of diminished signal are

typically seen on both T1-weighted and T2-weightedimages, although increased signal intensity may also benoted on T2-weighted images. Findings are even moreconspicuous on fat-suppressed, inversion recovery se-quences, where involved areas appear bright.29

If the clinical situation warrants, fine needle aspiration ofthe subcutaneous lesions may be useful to confirm thediagnosis. The finding highly suggestive of SCFN isnegatively stained, needle-shaped crystals within histiocytesand multinucleated giant cells. The main reason to establishthe diagnosis of this self-limiting entity is to differentiate itfrom other lesions that may require surgery. The principalclinical differential diagnosis includes other histologicallydistinct soft-tissue lesions of infancy such as rhabdomyosar-coma, the spectrum of fibrous lesions, hemangioma,neurofibroma, and sclerema neonatorum.28

Sclerema Neonatorum

Sclerema neonatorum is a rare disease of the newbornthat is characterized by a diffuse hardening of thesubcutaneous adipose tissues. As such, it is distinct from thelocalized lesions of SCFN. Sclerema appears within the firstpostnatal week in neonates who are severely ill withpneumonia, peritonitis, or other infectious or congenitaldiseases. Premature infants are particularly susceptible, andthe prognosis is grave. Sclerema may represent a disorder oflipolysis.30 Histologic analysis has demonstrated subcutane-ous fibrosis in all patients, with most having chronic dermalinflammation, epidermal thinning, and hypercollagenizationof the dermis.31

Plexiform Neurofibroma and SkinNeurofibromas

The presence of a plexiform neurofibroma is sufficientto warrant the diagnosis of von Recklinghausen’s diseaseeven in the absence of other associated stigmata. Aplexiform lesion can be seen as a fusiform or nodular mass,or as a tortuous enlargement of nerves that has beendescribed as a ‘‘giant nerve’’ or ‘‘bag of worms.’’ In thehead and neck, these lesions are often seen in thesubcutaneous tissues (Fig. 41-12). The degree and pattern ofcalcification vary.

Another manifestation of neurofibromatosis is the pres-ence of multiple neurofibromas on the skin, in addition toneurofibromas within the neck and facial region (Fig.41-13). A discussion of both neurofibromas and schwanno-mas also appears in Chapter 6.

Silicon Augmentation

Silicon and silicon products have long been used as tissueexpanders and for cosmetic surgery.32 Historically, siliconhad been injected subcutaneously to fill skin contours.Unfortunately, free silicon often invokes a granulomatousand fibrotic reaction that ultimately causes further deformity

FIGURE 41-11 Axial CT scan shows a partially infiltrative-appearingsubcutaneous soft-tissue mass (arrows) in each side of the face. Thisnewborn had subcutaneous fat necrosis.

41-8 NECK

FIGURE 41-12 Axial contrast-enhanced CT scan shows multiple massesprimarily in the right neck of this patient with neurofibromatosis. Some of themasses are partially cystic. In addition, in the subcutaneous right face there is anodular, poorly defined soft-tissue mass with a few scattered calcifications(arrow) representing a plexiform neurofibroma.

FIGURE 41-13 Coronal T1-weighted, fat-suppressed, contrast-enhanced MR image (A) shows an enhancing left hypopharyngealneurofibroma and multiple small, enhancing skin neurofibromas. AxialT2-weighted MR image (B) shows the same hypopharyngeal neurofibromaand the innumerable skin neurofibromas. Axial T1-weighted, fat-suppressed, contrast-enhanced MR image (C) on another patient showsneurofibromas in the right supraclavicular fossa, the right back soft tissues,and the anterior left neck. In addition, there are multiple skinneurofibromas.

of the overlying skin. On imaging, one sees thickening ofthe overlying skin, soft-tissue nodularity within the sub-cutaneous tissues, and scattered radiodensities (silicon)within this process (Fig. 41-14). If the fibrotic andgranulomatous reactions are severe enough, there is con-siderable deformity of the skin contour. Silicon productsare less frequently implanted today, and when used, theyare encased in containers that cause little reaction in theadjacent soft tissues.

Alloderm Augmentation

Numerous materials, both autologous and nonautolo-gous, have been used for augmentation of soft-tissue defectsin the facial region. There is no ideal material for soft-tissueaugmentation, as each material has its limitations. AlloDermdermal graft (LifeCell Corporation, Branchburg, NJ) com-bines the benefits of autografts and allografts. There is a verylow incidence of complications such as rejection, mobiliza-tion, absorption, dislocation, or extrusion. In addition, theuse of Alloderm minimizes two surgical problems: donorsite morbidity and lack of adequate tissue for reconstruction.Alloderm has been shown to be useful in facial plasticprocedures and the repair of burn injuries.33–42 On CT,Alloderm is of a fairly high attenuation, being greater thanthat of muscle but less than that of bone (Fig. 41-15). On MRimaging, if seen, it usually has a low-intermediate signalintensity on all sequences.

Foreign Bodies

In addition to surgically placed materials, foreignbodies may be identified following perforation or lacera-tion. Overall, perforations are uncommon, and their majormanifestations arise deep to the skin and subcutaneoustissues. Most foreign bodies in the neck are ingested and,after perforating the mucosa, migrate outside the pharynxor cervical esophagus. Oral cavity or oropharynx perfora-tions (especially those involving the tonsillar pillars) arenot uncommon in young children, who tend to walk, run,and fall with objects in their mouths; care must also betaken to exclude carotid injury. Finally, penetrating inju-ries from bullets, wires, knives, and other objects canresult in retained foreign bodies. Focal lucency within softtissues immediately following penetrating trauma oftenrepresents gas; however, hypodense foreign bodies madeof plastic, glass, or wood can appear similar. While thedensity of many of these bodies may not change overtime, that of rehydrated wood may gradually approachsoft-tissue density. Gas may also be generated by certainbacteria in infected wounds. If not removed, foreignobjects can cause abscess or pseudoaneurysm formation,or the foreign body can migrate into the chest, spine, oreven intracranially.43–56

In recent decades, the dietary preferences of many peoplehave changed to favor more fish and fowl and less meat. Thebones of chickens, quails, and so on are fairly large and wellossified, making identification on either plain films or CT

FIGURE 41-14 Axial contrast-enhanced cranial (A) and caudal (B) CTscans show areas of both increased density and intermediate density in theswollen subcutaneous soft tissues of both sides of the face. This patient hadhad silicon (increased density) injected in his cheeks several years earlierand then formed a foreign body reaction (intermediate density) to thesilicon. Axial CT scan (C) shows a silicon insert (arrow) overlying the rightzygoma. This is a fairly typical appearance of recent facial augmentationprocedures.

41-10 NECK

routine. However, special mention of the radiology of fishbones is warranted. Several studies have shown that CTexamination identifies almost all types of fish bones,whereas plain films often fail to identify some varieties.Factors that affect the imaging identification of fish bonesinclude the radiodensity of the fish bone, the orientation ofthe bone in relation to the imaging plane, and the locationof the bone (e.g., tonsil, hypopharynx, cricopharyngeus,esophagus). Although there is some variation amongreports, in general the bones of herring, salmon, mackerel,trout, blue fish, red fish, and pike are not well seen on plain

films.57–60 Thus, if one suspects that one of these varieties ofbones has perforated, CT may provide greater sensitivitythan plain film alone.

The bones of striped bass, sea bass, codfish, flounder,fluke, gray sole, haddock, halibut, porgie, red snapper,smelt, monk fish, plaice, gurnard, and white perch areall usually well seen on plain films and CT. Often on CT,the location of the fish bone is also identified bylocal enhancement due to an inflammatory reaction andsmall collections of air from the adjacent pharynx(Fig. 41-16).

FIGURE 41-15 Axial CT scans at narrow (A) and wide (B) window settings on a patient who has had alloplastsheet (arrows) augmentations in her cheeks.

FIGURE 41-16 Lateral scout film (A) and axial contrast-enhanced CT scan (B). In A, there is markedthickening of the prevertebral soft tissues and flattening of the mucosal surface. A radiodense foreign body (arrow)is seen anterior to the C3 vertebral body. In B, the foreign body is well seen (arrow) with adjacent air and a waterdensity phlegmon in the retropharyngeal space. In this patient, the foreign body was a flounder fish bone.

Chapter 41 Skin and Soft-Tissue Lesions 41-11

FAT-CONTAINING LESIONS

Ordinary Lipoma

Fatty or adipose tissue comprises 15% to 25% of thehuman body, although in obese individuals fat mayrepresent over 40% of body weight.61 Ordinary lipomashave been described in virtually every tissue of the body. Ingeneral, they are more common in females over the age of 40years; however, in the head and neck, they may occur morefrequently in males. The most common supraclavicularlocation is the posterior neck, with the anterior or lateralneck and the supraclavicular fossa also being frequent sites.Multiple lipomas may be seen in Gardner’s syndrome,multiple endocrine neoplasia, neurofibromatosis, or, rarely,in familial lipomatosis, although lipomas are so prevalentthat the vast majority are sporadic.9 Once fat is within alipoma, it cannot be utilized by the body, even in cases ofprofound starvation. Thus, when one gains weight a lipomamay enlarge, but when one loses weight the lipoma will notshrink.

Although there are various histologic types of lipoma(myxoid lipoma, angiolipoma, pleomorphic lipoma, spindlecell lipoma, and myelolipoma), on imaging they generallyhave smooth, noninfiltrative borders and contain almostexclusively fat (Fig. 41-17). Thus, on CT they have a lowattenuation, while on MR imaging they have high signal onT1-weighted imaging and intermediate to high signal on fastspin-echo (FSE) T2-weighted imaging. Approximately 8%of ordinary lipomas contain less than 95% fat, in which casedistinction from atypical lipomatous tumors may not bepossible.62 Rarely, hemorrhage can occur within an ordinarylipoma. In such cases, imaging shows a well-delineatedmass with areas of high attenuation on CT and high signal onboth T1-weighted and T2-weighted sequences.

Ultrasound characterizes lipomas as well-defined, com-pressible, elliptical masses with long axes parallel to theskin. Most are hyperechoic; however, one quarter areisoechoic or hypoechoic relative to muscle. Numerousechogenic lines are seen within the lipomas oriented parallelto the skin surface.63 Detection of distal shadowing or distalaugmentation suggests a different diagnosis.

Infiltrative (Intramuscular) Lipoma

Intramuscular lipomas are uncommon, benign unencap-sulated tumors, also referred to as infiltrating lipomasbecause of their infiltrative growth pattern. Histologically,monovacuolar fat tissue is seen between muscle fibers and,in extreme cases, the muscle may be totally replaced by fattytissue. Careful pathologic examination is necessary to avoidthe mistaken diagnosis of a well-differentiated liposarcoma.Complete resection is often difficult, and the postoperativerecurrence rate is 3% to 62%. In fact, incomplete resection isfavored because development of muscle dysfunction due tofatty infiltration is gradual, and the patient tends tocompensate well through recruitment of other muscles. Bycomparison, the rapid loss of function secondary to thesurgical removal of a muscle is, in general, poorly tolerated.

On CT, the fatty mass is typically centered within the

normal areas of adipose tissue within the neck. The MRfindings of intramuscular lipoma can vary from those of ahomogeneous ordinary lipoma to a large, inhomogeneouslesion with an infiltrative margin. The presence of infiltra-tive margins and intermingled muscle fibers in an intramus-cular lipoma indicates a benign lesion rather than amalignancy, and such ingrowth of fatty tissue among themuscle fibers may be seen in up to one third of cases (Fig.41-18).64 In addition, uninodularity of the mass is helpful indifferentiating intramuscular lipoma from the usuallymultinodular well-differentiated liposarcoma.65–70

Madelung’s Disease

Multiple symmetric lipomatosis, described in Germanyby Madelung in 1888 and in France by Launois andBensaude in 1898, is a rare disease of unknown etiology. Itis characterized by the presence of compartmentalized, butunencapsulated, fatty deposits in the neck and upper body.These deposits usually grow slowly, and their initialconsequence is purely cosmetic. Rarely, however, they canlead to compression of the larynx, trachea, and cervicalesophagus.

This disease usually affects middle-aged males ofMediterranean descent with a history of alcohol abuse.Although most cases have been sporadic, some investiga-tors believe this disorder may be hereditary, and it isthought that this pathology originates from an alteration inlipid metabolism. Surgical removal of the fatty masses is thetreatment of choice; however, recurrences are common.71

The fatty deposits can be present virtually anywhere in theneck, but they are predominantly seen in the posteriorneck deep to the trapezius and sternocleidomastoidmuscles, in the supraclavicular fossa, and between theparaspinal muscles. Less often, the excess fat is seen in theanterior neck, superior mediastinum, pretracheal and pre-vertebral spaces, and over the cheeks.72 On imaging, thecompartmentalized appearance of the fat (Fig. 41-19)distinguishes the findings from obesity, in which there is ageneralized increase in fat within the subcutaneous tissues(Fig. 41-20). The masses typically show no calcification orossification, and there is no invasion of adjacent vascularstructures.72

Liposarcoma

Liposarcomas represent 15% to 18% of all soft-tissuemalignant tumors. They typically develop in the fourththrough sixth decades and are more common in males.Liposarcomas are found mainly in the deep soft tissues,unlike lipomas, which usually arise superficially. With fewexceptions, liposarcomas are believed to develop de novoand not from ordinary lipomas. About 3% occur in the headand neck, with most occurring in the neck and cheek.61 Thetreatment of choice is wide surgical resection. Of the 25% to46% of liposarcomas that recur, most are of the round cell orpleomorphic varieties.

On CT, liposarcomas can appear as ordinary lipomasor they can have variable scattered soft-tissue density(Fig. 41-21). In the more extreme cases, little fat is seen

41-12 NECK

(Fig. 41-22). Well-differentiated liposarcomas can have avariety of MR imaging appearances. Typically, they havefeatures suggestive of a benign lipoma (a well-defined masswith high T1-weighted and low-intermediate T2-weightedspin-echo [SE] signal intensities, with little or no contrastenhancement). In less well differentiated liposarcomas

(myxoid, pleomorphic, and round cell), the majority of thetumor typically has a low T1-weighted signal intensity, andonly scattered fatty islands and septa may be seen.T2-weighted images usually show most of the mass to be ofintermediate to high signal intensity, with fatty islands ofrelatively low to intermediate signal intensity.73 Much

FIGURE 41-17 A, Axial contrast-enhanced CT scan shows a well-delineated fatty mass in the subcutaneoustissues of the back of the neck. B, Axial contrast-enhanced CT scan shows a well-delineated fatty mass in thesubcutaneous tissues of the left neck. Despite the size of the mass, there are smooth, noninfiltrating borders. AxialT1-weighted image (C) shows a well-circumscribed high signal intensity mass situated between the left paraspinalmuscles. The lesion is isointense to normal fat. D, Axial T1-weighted, fat-suppressed, contrast-enhanced MR imageshows that the mass suppresses like normal fat. All of these patients had ordinary lipomas.

Chapter 41 Skin and Soft-Tissue Lesions 41-13

FIGURE 41-18 Axial contrast-enhanced CT scan shows a fat attenuationmass in the right neck. The mass invades the right sternocleidomastoid muscle.This patient had an infiltrating lipoma.

FIGURE 41-19 Axial CT scans (A and B) show multiple discrete fattymasses in the subcutaneous tissues of the back. Axial T1-weighted MRimage (C) shows the well-delineated fatty collections in the posterior neck.This patient had Madelung’s disease.

coarser stromal enhancement is seen in the less differenti-ated tumors.

INTERSTITIAL LESIONS

Fibrosarcoma

Although fibrosarcoma was once described as beingamong the most common sarcomas, the improved character-ization of previously misdesignated fibromatoses has led to alower reported incidence of fibrosarcoma. As a result,fibrosarcoma now lags well behind malignant fibroushistiocytoma in frequency.74 Although it can be seen at anyage, fibrosarcoma is most common in the fifth througheighth decades; a smaller peak is seen in the neonatal period

and in infancy. There is an increased incidence in males andin sites of previous burn or radiation, but other radiation-induced sarcomas, such as malignant fibrous histiocytoma,are more common.

Fibrosarcoma typically presents as a painless, slowlygrowing mass. It can arise superficially, from deepsubcutaneous tissue, or deep within the soft tissues of theneck. Superficial tumors tend to be detected at a smaller sizethan deeper tumors.74 The histologic appearance varies, withlower-grade tumors seen as solid and higher-grade lesionsdemonstrating necrosis and hemorrhage. Distinction oflower-grade lesions from aggressive fibromatosis can bedifficult, but only fibrosarcoma will metastasize. Theapparently worse prognosis of fibrosarcoma in the head andneck compared with extremity lesions may relate to theinability to obtain adequate tumor margins rather thandiffering biologic activity.

On imaging, the findings of fibrosarcoma are nonspe-cific. Low-grade lesions are homogeneous on CT andhypointense on T1-weighted and T2-weighted images.Mild to moderate enhancement is seen on MR imaging butnot on CT.75 Distinction from other aggressive fibroma-toses can prove difficult, as they can appear quite similar.However, the presence of necrosis strongly favors thediagnosis of a higher-grade fibrosarcoma. Imaging, partic-ularly MR imaging, has played a major role in definingthe extent of these tumors. This is important for propersurgical planning or, if indicated, for planning of properradiation fields.75

FIGURE 41-20 Axial CT scan shows extensive fat in the subcutane-ous soft tissues of an obese patient. There are no discrete, well-definedcollections of fat, as seen in Madelung’s disease.

FIGURE 41-21 Axial contrast-enhanced CT scan shows a nonhomo-geneous but primarily fatty mass in the posterior left neck. Portions of thelesion contour are well defined; others are poorly seen. This patient had aliposarcoma.

FIGURE 41-22 Axial contrast-enhanced CT scan on a patient who hadhad prior surgery on the pharynx and left neck for a liposarcoma. Therewas a sudden enlargement of the left neck, and this CT scan shows awell-defined, slightly enhancing, nonhomogeneous mass. At surgery, thiswas found to be a recurrent liposarcoma that had hemorrhaged.

Chapter 41 Skin and Soft-Tissue Lesions 41-15

Benign Fibrous Lesions (Fibromatoses)The fibromatoses are a heterogeneous group of histologi-

cally benign fibroproliferative disorders that share character-istics with both reparative processes and neoplasias. Theymay be localized or diffuse, symmetric or asymmetric,regress spontaneously or resist treatment and recur. Fibro-matoses are often recognized in childhood, but they canoccur at any age. Although most follow a benign course,compromise of vital structures may occur.61 As a group,they do not metastasize.76

The etiology of these fibromatoses is unknown, and theclassification of these lesions is mainly based on theirclinical findings. Although a number of lesions are classifiedas fibromatoses, this section will only deal with desmoidfibromatosis, congenital fibromatosis, nodular fasciitis andproliferative fasciitis.

Desmoid TumorThe term fibromatosis without any further qualifiers is

generally taken to indicate desmoid fibromatosis, which isan infiltrative process not limited to the fascia. Rather, itarises from musculoaponeurotic structures and invades thecontiguous tissues. Some pathologists consider them well-differentiated fibrosarcomas, particularly when scatteredmitotic figures are identified. Unlike abdominal walldesmoids, which are more common in women, there is noclear gender predilection in head and neck desmoids. Theyare seen in all age groups, although there is a higherincidence in the first few decades of life.74 Patients withGardner’s syndrome are at increased risk for developingdesmoids.

These lesions are typically firm or hard and usuallypainless, although occasionally they are tender. Most neckdesmoids are found in the upper neck; however, those seenmore inferiorly may be more difficult to manage, as they caninvolve the great vessels, trachea, and brachial plexus. Theyare locally invasive but do not metastasize (Fig. 41-23).61, 74

Surgery is the treatment of choice, and while lesions oftenextend 2 to 3 cm beyond their apparent boundaries, somecases with positive surgical margins may not recur.Irradiation and chemotherapy are reserved for recalcitrantcases.

Congenital Fibromatosis (Generalized and Localized)Congenital generalized fibromatosis (infantile myofibro-

matosis) is a rare disease that starts in utero; however,additional lesions may continue to develop after birth. Itpresents as multiple superficial tumors of the skin andsubcutaneous tissues. However, deep lesions involving theheart, lungs, skeletal muscles, viscera, and/or bones alsooccur, and many patients succumb to the disease. If theinfant survives the first few months of life, the tumors oftenregress spontaneously over the next 6 to 18 months.61

Somewhat paradoxically, fibrous-rich tissues such as ten-dons and fascia are rarely affected.

Congenital localized fibromatosis, which may be morecommon than the generalized form, presents at or just afterbirth and is localized to just one body area. Typically, thetumors arise in the subcutaneous tissues, skeletal muscle, orbone, and most nonvisceral lesions spontaneously regress.Recurrence following resection of solitary lesions isuncommon.

Histologically, the mesenchymal cells appear moreimmature than those seen in desmoid tumors, and there isoccasional necrosis with calcification that is not seen inother fibromatoses.74 On CT, the fibromatoses usually areinfiltrating lesions that have an attenuation equal to or higherthan that of muscle and that enhance significantly aftercontrast administration. On MR images, these lesionsusually are heterogeneous and may be either of intermediateor low signal intensity on T2-weighted images. The signalon T1-weighted images is low to intermediate, and there isstrong enhancement after contrast administration.77, 78

Nodular Fasciitis (Pseudotumor of the Skin)Nodular fasciitis is a benign, nonneoplastic, self-limited

fibroproliferative disorder. Its importance lies in its occa-sional pathologic confusion with a sarcoma. The head andneck region is the second most common site, lagging behindthe upper extremities, where almost half of the lesions arefound. Most often, this entity presents in the superficialfascia as a subcutaneous movable nodule that may be tenderor painful. However, it also can arise from the deep fasciaand may present as an intramuscular mass. Nearly half of thelesions grow rapidly over a few weeks and then slowlydecrease in size over the next weeks to months. About 30%of the lesions show no change in size after presentation.Trauma or infection may increase the risk of developingnodular fasciitis, which is believed to represent a reactive orinflammatory process of the myofibroblasts that are nor-mally concerned with skin repair.79 Local excision is thetreatment of choice, and a local recurrence (7% of cases)need not be resected if the diagnosis is established.

On CT, subcutaneous lesions are well defined by theadjacent fat, but intramuscular lesions may be poorlydefined, usually with an attenuation slightly less than that ofskeletal muscle. The lesions are well seen by MR imaging;intramuscular lesions are hyperintense to skeletal muscle onT1-weighted and hyperintense to fat on T2-weighted SEimages. Subcutaneous lesions may be hypointense toskeletal muscle on all SE pulse sequences or hyperintense onT2-weighted images. Fairly pronounced enhancement oc-curs after contrast administration (Fig. 41-24). Becausethere are no unique imaging findings, nodular fasciitis mustbe included in the preoperative differential diagnosis ofsmall soft-tissue masses.80, 81 Among other lesions to beconsidered in this differential diagnosis are neurofibroma,schwannoma, fibrous histiocytoma, fibromatosis, fibrosar-coma, myxoid liposarcoma, and myxofibrosarcoma.

Proliferative Fasciitis

Though used by many researchers as a synonym fornodular fasciitis, the term proliferative fasciitis should bereserved for a peculiar subcutaneous and facial lesion thatmay represent the cutaneous counterpart of proliferativemyositis. Proliferative fasciitis clinically is similar tonodular fasciitis except that it occurs in older patients and isless nodular and less defined, growing in the superficialfascia. Lesions may be painful, but the clinical course isbenign and recurrences are rare.61

41-16 NECK

FIGURE 41-23 Axial cranial (A) and caudal (B) contrast-enhanced CTscans show a large, homogeneous mass (M ) in the left neck filling theposterior triangle of the neck and extending into the supraclavicular fossa.Although the upper boundaries of the mass are fairly sharp, the lowerborders merge with the adjacent muscles. Axial T1-weighted MR image (C)on another patient shows an intermediate signal intensity mass in theposterior triangle of the left neck. The lateral boundary is fairly welldelineated; however, the medial contour is poorly defined as it projectsbehind the pharynx and encases the carotid sheath (arrowhead ). CoronalT1-weighted, contrast-enhanced MR image (D) on the same patient as in Cshows enhancement of the mass. Axial T2-weighted MR image (E) on adifferent patient shows a high signal intensity mass in the left neck.Although some of the ventral margins are fairly well defined, the posteriorboundaries are more infiltrative. All of these patients had fibromatosis.(Figs. 41-23C–E courtesy of Dr. Larissa Bilaniuk.)

Chapter 41 Skin and Soft-Tissue Lesions 41-17

Necrotizing Fasciitis

Necrotizing fasciitis is a potentially fatal bacterialinfection that spreads within fascial planes. Although it israre in the neck, possibly due to its relatively richvascularity, this entity is included because of the potentiallydevastating sequelae of a delayed diagnosis.82 Although itwas once attributed primarily to extension of dental orpharyngotonsillar infections, numerous case reports haverecently implicated sinus infections, epiglottitis, insect bites,radiotherapy, and trauma.83–86 Inadequately treated infec-tions can lead to mediastinal extension, considerablenecrosis of the surrounding soft tissues and skin, andsystemic toxicity.

Relatively constant CT findings in surgically provennecrotizing fasciitis include diffuse thickening and infiltra-tion of the skin and subcutaneous tissue (cellulitis),enhancement and/or thickening of cervical fascia (fasciitis)and dominant muscles (myositis), and compartmental fluidcollections.87 Variable findings include soft-tissue gas,mediastinitis, and effusions. Subsequent CT imaging candemonstrate clinically unsuspected progression of disease,allowing for debridement sooner than would otherwise beconsidered.87 MR imaging is sensitive for both cellulitis andfasciitis. In cellulitis without fasciitis, there may beenhancement of subcutaneous tissues or superficial fascia, aswell as subcutaneous thickening and fluid collections. Whenfasciitis is present, however, there is thickening, enhance-ment, or increased T2-weighted signal intensity within thedeep fascia, and deep fluid collections are not uncommonlyseen. This fluid represents necrosis or abscess formation, thedistinction of which can be difficult, as both are seen as areaslacking enhancement.88

MUSCLE-RELATED LESIONS

Levator Claviculae Muscle

The levator claviculae is a normal muscle found in 2% to3% of the population. The muscle arises from the anteriortubercles of the transverse processes of the upper cervicalvertebrae, runs down the neck medial to the sternocleido-mastoid muscle, and inserts onto the middle third or lateralhalf of the clavicle (Fig. 41-25). It may be unilateral orbilateral. The imaging importance of this muscle lies in itsrecognition as a normal structure rather than as an enlargedlymph node, an unenhanced blood vessel, or some othermass.89, 90

Denervation Atrophy

Denervation of a muscle leads to predictable changes thatend in a small, atrophic muscle, much of which is replacedby fat. Acute and subacute denervation results in aneurogenic edema that actually causes some muscleenlargement and high T2-weighted signal intensity on MRimaging.91, 92 Chronic denervation is best seen on T1-weighted images, manifest as a loss of muscle bulk withdiffuse areas of increased signal intensity within the musclecorresponding to fatty replacement. On CT, a similar patternof fatty changes is seen, but it is slightly less well definedthan on MR images. The rate of progression varies widely,with some investigators showing acute/subacute edematousfindings persisting for up to 48 months after denervation insome patients and chronic fatty changes developing as earlyas 2 months in others.92 On both CT and MR imaging,

FIGURE 41-24 Axial T2-weighted MR image (A) shows a hyperintense nodule in the right paraspinal muscles.Axial T1-weighted, fat-suppressed, contrast-enhanced MR image (B) shows an intensely enhancing nodule. Theappearance is not specific, as a primary muscle tumor or metastasis could have a similar appearance. This patient hadnodular fasciitis.

41-18 NECK

end-stage fat replacement often results in fatty tissue withoutany identifiable muscle fibers (Fig. 41-26).

Muscle Hypertrophy

Muscle hypertrophy can develop as a result of exercise,in association with myotonic disorders (increased spontane-ous activity), or idiopathically (some cases of masticatormuscle hypertrophy). In true muscle hypertrophy, themuscle is enlarged but otherwise normal on all imaging.There also can be a pseudohypertrophy of muscle due toinfiltration of the muscle by muscular dystrophies, amyloid-osis, sarcoidosis, thyroid disease, and parasitic infestations.Lastly, a myositis can enlarge a muscle. On CT, the enlargedhypertrophic muscle may appear normal in density, butabnormal MR signal intensity is seen in most muscles thatare enlarged due to pseudohypertrophy or a myositis.

A fairly common example of exercise muscle hypertro-phy in the head and neck occurs with masticator musclehypertrophy and in patients after a radical neck dissection(Fig. 41-27). After surgery, there is shoulder drop followingdenervation of the trapezius muscle; most patients, there-fore, recruit the ipsilateral levator scapulae muscle to elevatethe scapula. The resulting hypertrophy of the levator canbeen seen as a ‘‘pseudomass’’ on imaging, often misinter-preted as a tumor recurrence. Similarly, patients who liftweights often develop hypertrophy of the lower neck, upperback, and shoulder muscles, although these changes tend tobe symmetric bilaterally.

Fibromatosis Colli (Sternomastoid orSternocleidomastoid Tumor)

Torticollis may be either congenital or acquired. Thecause may be muscular, neurogenic, infectious, neoplastic,posttraumatic, or even psychogenic. When torticollis iscaused by a fibrocollagenous infiltration of the sternocleido-mastoid muscle with a palpable mass in the newborn, thedisease is called fibromatosis colli or sternocleidomastoid

tumor. This must be distinguished from muscular torticollis,which is a tightening of the muscle without a palpable mass.However, between 15% and 20% of patients with fibromato-sis colli progress to muscular torticollis despite therapy.61

The right neck is affected in 75% of cases, and rarely,fibromatosis colli may be bilateral. About 70% of the casespresent between birth and 2 months of age. Most casesspontaneously regress without resulting deformity, andconservative therapy is the treatment of choice. Althoughmultiple explanations of the exact etiology have beenoffered, the cause remains unknown.93, 94

Sternocleidomastoid tumor presents as a benign, firm,fibrous swelling predominantly involving the middle orinferior third of the sternocleidomastoid muscle (Fig.41-28). This pseudotumor affects 0.4% of infants in theirfirst few weeks of life, with the vast majority showingcomplete regression over the ensuing few months. Onultrasound, fibromatosis usually appears as a hyperechoicmass or as diffuse enlargement of the sternocleidomastoidmuscle of mixed echogenicity; other patterns are identifiedbut are less common. The adjacent soft tissues shouldremain normal.95 Although the signal characteristics relativeto normal muscle may vary, signal intensity in fibromatosisis slightly increased on T2-weighted images and moresignificantly increased on gradient-recalled T1-weightedimages; the SE T1-weighted signal intensity is essentiallynormal.96

Muscular Torticollis

Pathologically, muscular torticollis shows a limitedcollagenous and/or fibroblastic proliferation that does notcause a mass. It thus might be considered within thespectrum of fibromatosis colli, although 73% of cases ofmuscular torticollis present after 1 year of age. If it presentsprior to 6 months of age, passive stretching may provebeneficial. After that age, a tenotomy may have to beperformed.61

Congenital muscular torticollis, or idiopathic spasmodictorticollis, may be of unknown etiology, or may be related to

FIGURE 41-25 Axial cranial (A) and caudal (B) contrast-enhanced CT scans through the neck show a left-sidedlevator claviculae muscle (arrows). The levator lies deep to the sternocleidomastoid muscle in the midneck andlateral to it in the lower neck. (Courtesy of Dr. David Rubinstein.)

Chapter 41 Skin and Soft-Tissue Lesions 41-19

trauma or found in conjunction with a variety of intracranial,atlantoaxial, and spinal pathology.94, 97–125 Because of theassociation of congenital muscular torticollis with otherintrauterine positioning disorders, it has been postulated thathead positioning in utero may selectively injure thesternocleidomastoid muscle, leading to development of acompartment-type syndrome.117 Singer et al. studied torti-collis patients with CT and MR imaging and found signssuggestive of fibrosis within the sternocleidomastoid, whichwas confirmed at surgery.113 Although congenital musculartorticollis is usually discovered in infancy or childhood, it

may also present in adolescence or young adulthood. Itshould be considered in the differential diagnosis ofnondystonic causes of abnormal head posture.

In a series of pediatric patients who presented with acutetorticollis, including some without a history of trauma,almost two thirds (13/21) had atlantoaxial rotatory subluxa-tion (AARS) on CT.126 It has been suggested that torticollisrelated to AARS may not adequately resolve until thissubluxation is addressed, either with fluoroscopically guidedreduction or by fusion.127 These reports underscore theimportance of the cervical spine CT examinations in

FIGURE 41-26 Serial axial contrast-enhanced CT scans from cranial (A) to caudal (D) on a patient who has hadskull base surgery with damage to his right cranial nerves V, VII, and IX to XII. In A, there is marked atrophy of theright sternocleidomastoid muscle (arrowhead ) and fatty replacement of the right-sided tongue muscles. As a result,the right base of the tongue prolapses back farther than the left side, possibly suggesting the presence of a mass onthe right. The right internal pterygoid and masseter muscles are also smaller than their left-sided counterparts. In B,there is atrophy of the right sternocleidomastoid (arrowhead ) and trapezius muscles. There also is atrophy of themuscles in the right side of the floor of the mouth. In C, the marked atrophy of the right sternocleidomastoid(arrowhead ) and trapezius (arrow) muscles is clearly evident. In D, an axial contrast-enhanced CT scan through thelower neck of a different patient who has had a left radical neck dissection shows denervation atrophy of the lefttrapezius muscle (arrowhead ). The right trapezius is normal, but its bulk could be mistaken for a mass (arrow).

41-20 NECK

evaluating the cause of acute torticollis that does not resolvespontaneously.

In 1969, Snyder described paroxysmal torticollis, whichdeveloped in patients between ages 2 and 8 months. Thespells of head tilting lasted for a few hours to three days andwere occasionally accompanied by pallor, vomiting, andagitation at the beginning of the spells. In most children, thespells stopped spontaneously by age 5 years.128 This diseasemay have a familial occurrence, and 12% of patients with

benign paroxysmal vertigo of childhood previously hadparoxysmal torticollis of infancy.129

The evaluation of torticollis is often performed byultrasound, which shows a diffuse enlargement of thesternocleidomastoid muscle. The abnormality may be eitherisoechoic or hypoechoic, depending on the age of the lesion.Although the enlarged muscle may be mistaken for a mass, italways moves with the muscle on real-time sonography.130

Because ultrasound is always abnormal in patients with

FIGURE 41-28 Axial CT scan (A) shows an enlarged left sternocleidomastoid muscle of slightly lower attenua-tion than that of normal muscle in this infant. Axial T1-weighted, contrast-enhanced MR image (B) on another patientshows enhancement of a grossly enlarged right sternocleidomastoid muscle (arrow). Both of these patients had fibro-matosis colli. (Courtesy of Dr. Larissa Bilaniuk.)

FIGURE 41-27 Axial T1-weighted MR image (A) shows bilateral enlargement of the masseter muscles (M ) inthis patient with masseteric hypertrophy. In B, an axial contrast-enhanced CT scan on a patient who has had a leftradical neck dissection shows atrophy of the left trapezius muscle (arrowhead ). There is early hypertrophicenlargement of the left levator scapulae muscle (arrow).

Chapter 41 Skin and Soft-Tissue Lesions 41-21

fibromatosis colli, this study should be included in theevaluation of infants with this suspected condition.131

On CT, the enlarged sternocleidomastoid muscle isisodense to normal muscle and either homogeneous orslightly inhomogeneous. On MR images, the muscle can beeither isointense or of a lower signal intensity than normalmuscle, either homogeneous or slightly nonhomogeneous,and the caudal portion of the muscle is usually more affectedthan the cranial margin. It is important to exclude other neckmasses such as branchial cleft cysts, cystic lymphangiomas,and malignancies such as rhabdomyosarcoma and neuro-blastoma.130

Myositis

Skeletal muscle may be inflamed secondary to anadjacent cellulitis and/or abscess. In such instances, techni-cally the term myositis can be applied. The muscle typicallyis swollen and enhances on both CT and MR images (Figs.41-29 and 41-30). On MR imaging, the muscle has higherthan normal T2-weighted signal intensity, and there isevidence of inflammation in adjacent structures.

The term proliferative myositis describes a rapidlygrowing pseudosarcomatous lesion of skeletal muscle. In thehead and neck, it usually affects the sternocleidomastoidmuscle. It tends to occur in older patients, and it is not seen

FIGURE 41-29 Axial contrast-enhanced CT scan shows cellulitis inthe left neck. There is thickening of the skin, widening of the subcutaneousfat with increased attenuation, and thickening of the platysma (arrow) as aresult of an inflammatory myositis.

FIGURE 41-30 Axial T1-weighted (A) and T2-weighted (B) MR images show minimal thickening of theanterior left sternocleidomastoid muscle and an area of high T2-weighted signal intensity. This patient had a leftsubmandibular gland acute sialadenitis with a cellulitis. He was treated with antibiotics, and although the other signsof infection subsided, he had persistent muscle pain in his sternocleidomastoid muscle. This was an inflammatorymyositis.

41-22 NECK

in children. Rarely, foci of osteoid or bone may be present,and simple excision is curative.61

Focal myositis is a benign, inflammatory pseudotumor ofskeletal muscle. It grows rapidly and involves a singlemuscle. Both children and adults are affected. It is rare in thehead and neck but has been reported in the sternocleidomas-toid muscle, the submental region, and the buccal region.Surgery is curative.

Myositis Ossificans

Myositis ossificans occurs in two forms. The morecommon variant is myositis ossificans circumscripta(MOC), which usually is a localized process that occursoutside the head and neck region. The rarer and more diffuseform of the disease is myositis ossificans progressiva. MOCis an uncommon disease that has been reported to occur inpatients after trauma, burns, and infections and in patientswith no known underlying pathology. Although the etiologyremains unknown, most investigators believe that MOCrepresents a localized nonneoplastic, reactive process thatresults in the proliferation of undifferentiated mesenchymaltissue that then infiltrates into the surrounding soft tissues.Suggested etiologies include ossification of a hematoma,tearing of periosteum allowing subperiosteal cells to invadethe muscle, and metaplasia of muscle and connective tissue.Although MOC can involve any skeletal muscle, it isuncommon within the head and neck; it has been reported inthe masseter, medial pterygoid, temporalis, buccinator,geniohyoid, genioglossus, sternocleidomastoid, and paraspi-nal muscles. Although MOC occurs in both males andfemales, the most commonly affected group is young,athletic males. In cases where there is a definite history oftrauma, the time period between injury and clinical detectionof MOC ranges from 3 weeks to 20 years. From the time ofdocumented trauma, radiographic evidence of calcificationin MOC can be seen as early as 2 to 4 weeks and maturebone as soon as 4 to 5 months.132

On CT, mature MOC shows a peripheral shell ofcalcification and/or ossification in a focal mass. However,very early calcification may be misinterpreted as enhance-ment, especially if the protocol for CT imaging of the neckdoes not include both pre- and postcontrast studies. Earlyimaging may also suggest a neoplastic mass and adjacentinflammation. The appearance is consistent with the earlyhistologic description of central fibroblast proliferation andmyofibroblasts with associated edema (Fig. 41-31),133, 134

which may hinder histopathologic distinction of MOC frommalignancy. Therefore, the possibility of MOC should becommunicated to the pathologist if a biopsy is performed.

Three phases of evolution of MOC have been described:a pseudoinflammatory phase, a pseudotumoral phase, and achronic phase. Imaging findings depend on the phase of thedisease. On T2-weighted SE images, early lesions typicallyshow a nonhomogeneous soft-tissue mass with extensivesurrounding edema. Postgadolinium images often showmarked enhancement of the mass. Mature lesions aretypically better defined, without associated edema. MRimaging, however, is not definitive in its ability to excludemalignancy.

MR imaging of mature lesions has shown well-defined,

inhomogeneous masses with signal intensity close to thatof fat on both T1-weighted and T2-weighted images,hypointense rims, and no surrounding edema (Fig. 41-32).On MR imaging, the differential diagnosis includes an earlyabscess, necrotic adenopathy, and neoplasm. The imagingappearance of pyomyositis and polymyositis can also mimicthat of early MOC lesions on both CT and MR imaging. Iffine needle aspiration is utilized to arrive at a diagnosis ofMOC, a sample of the periphery of the lesion must beobtained.132

Muscular Dystrophies

The muscular dystrophies are a group of primary muscledisorders that are hereditary in nature. The underlyingbiochemical defects are not well described. Of the dystro-phies, the primary one that affects the neck muscles isfascioscapulohumeral (FSH) dystrophy. Outliers dystrophy,which lies on a spectrum somewhere between Duchenne’sand Becker’s muscular dystrophies, affects the flexormuscles of the neck so that the supine patient cannot lift thehead against gravity. Walking is also affected after the ageof 12 years. Other dystrophies, such as Emery-Dreifussmuscular dystrophy and scapuloperoneal dystrophy, affectthe shoulder muscles and may uncommonly involve musclechanges seen on neck imaging studies. There also areisolated dystrophies that seem to affect a single group ofmuscles, such as the extensor back muscles.

FSH dystrophy is inherited as an autosomal dominanttrait. Its prevalence is about 1 per 100,000 population. Thecause remains unknown. Variable facial weakness is usuallyfirst noted in the second decade of life. Shoulder weaknessespecially affects the scapular fixators. Leg weakness alsomay occur. A more severe form of the disease occurs ininfancy. Treatment is supportive.135

On CT, there is almost total fatty replacement of theaffected muscles (Figs. 41-33 and 41-34). On MR imaging,the muscle has signal intensities close to those of fat, and thenormal low muscle signal intensity is absent.

Myotonic Dystrophy

Myotonic dystrophy is one of the most commondystrophies, with an incidence of 2.5 to 5 per 100,000population. It is estimated that between 1/20,000 and 1/7500people carry the gene mutation for the disease. Thesyndrome is inherited as an autosomal dominant trait withvariable transmission. The abnormality has been mapped asa CTG trinucleotide repeat sequence on the q13.3 band ofchromosome 19, and when the disease is inherited from themother, it tends to be more severe. Paternal transmission israre.136, 137

Typically, the disease presents in the second to fourthdecades of life; however, children can also be affected.Commonly, the small muscles of the hands and the extensormuscles of the forearms are the first to atrophy. However, insome patients, ptosis and facial muscle atrophy are the initialfindings. Usually affected are the masseter and sternocleido-mastoid muscles, leading to a deformed mandible and a‘‘swan neck.’’ The association of frontal baldness and a

Chapter 41 Skin and Soft-Tissue Lesions 41-23

FIGURE 41-31 Axial contrast-enhanced CT scans (A and B) of the neck obtained 1 week after a 38-year-oldmale complained of neck pain. In A, there is a vague area of low attenuation and fullness in the left paraspinalmuscles (white arrow), and there is a faint curvilinear density (black arrow) that could be interpreted asenhancement within the mass. A more caudal scan (B) shows a vague low attenuation and fullness in the leftparaspinal muscles (arrow). Unenhanced CT scans (C and D) obtained 1 month after onset show that in C there isnow a well-defined calcified/ossified density (black arrow) within the enlarged, otherwise low-attenuation (whitearrow) left paraspinal muscles. This radiodensity corresponds to the area that may have been attributed toenhancement on the prior study (A). In D, there is enlargement and low attenuation in the left paraspinalmuscles (arrow).

41-24 NECK

wrinkled forehead give the patient a distinctive appearance.Virtually all muscles can be affected, and most patients areconfined to either a wheelchair or bed by the age of 15 to 20years. Myotonia may precede muscle weakness (Fig. 41-35).Opacity of the lenses is common.

Also associated is a generalized hyperostosis affectingthe skull and skull base. CT findings include thickened bonewithin the calvarium, mastoid portion of the temporal bone,petrous pyramid, anterior clinoid process, dorsum sellae,and clivus. Involvement of the glenoid fossa may lead todislocation of the temporomandibular joint. Lytic andnonexpansile, sclerotic changes have also been seen in thetemporal bone.138, 139 Patients may also have huge frontalsinuses and a small sella turcica. Less common findingsinclude craniokyphosis, a small nasal angle, narrowing ofthe internal auditory canals, hypotelorism, and enlargementof the mandible. Changes may be unilateral or bilateral. Forthe most part, the areas of expanded bone have a grosslynormal cortical and trabecular pattern. The cause of thesebony findings is still unknown.140, 141

Rhabdomyosarcoma

Rhabdomyosarcoma (RMS), the malignant tumor ofstriated muscle, accounts for 8% to 19% of all soft-tissuesarcomas, and 35% to 45% of such sarcomas occur in thehead and neck. Almost all tumors (98% to 99%) containingskeletal muscle are RMS, with the small remainder

representing rhabdomyomas.74 RMS is primarily a tumor ofchildren and young adults, with most cases arising inpatients under 12 years and 43% seen in patients less than 5years of age. It is the most common sarcoma in children andthe seventh most common malignancy in children overallafter leukemia, central nervous system tumors, lymphoma,neuroblastoma, Wilms’ tumor, and bone cancer.61 Varietiesinclude embryonal, alveolar, pleomorphic, botryoid, andmixed types. Most pathologists consider mixed RMS to becomposed of two or more of these histologic types.75

More than half of RMS are of the embryonal variety, andof those, 70% to 90% arise in the head and neck orgenitourinary tract. Most are seen in patients less than 10years of age; however, nearly one quarter of cases are seenafter the second decade. Regional nodal metastasis occurs in10% to 38% of cases.61

Alveolar RMS is the second most common variety,representing approximately one fifth of all cases of RMS. Itoccurs mainly in patients 15 to 25 years of age and primarilyaffects the extremities and trunk. Only 18% of cases occur inthe head and neck. Nodal metastases are most common inthis variety, with regional lymph node involvement seenin 33% of cases and regional or distant nodal disease in 75%to 85%.61, 75

Botryoid RMS differs from embryonal RMS only in itsgross appearance. About 75% of these tumors arise in thevagina, prostate, or bladder. The remaining tumors arise inthe head and neck or bile ducts. Most patients are between 2and 5 years of age.

FIGURE 41-31 Continued. CT scans (E and F) obtained 4 months after onset show that in E thecalcified/ossified density remains on this unenhanced image; however, the low attenuation and swelling of the leftparaspinal muscles are no longer seen. Following contrast administration (F), there is now a symmetric and normalappearance of the paraspinal muscles. These findings illustrate the progression of myositis ossificans.

Chapter 41 Skin and Soft-Tissue Lesions 41-25

Pleomorphic RMS is seen primarily in patients 40 to 60years of age, with only 6% discovered in patients less than15 years of age. Most cases arise in the extremities, and only7% affect the head and neck. Metastasis is primarilyvascular, and only 9% of patients have regional nodalmetastasis.61 Survival is poorest with this variety of RMS.75

Clinically, RMS is usually a solitary, rapidly enlarging,firm mass that involves a striated muscle. Since theintroduction of radiation and chemotherapy in RMS

treatment, there has been significant improvement inlong-term survival (now 85% or better).74 The prognosiscorrelates more closely with extent of tumor involvementthan with tumor type. By location, tumor in the orbit tends tobe more localized and has a lower incidence of lymph nodemetastasis than other supraclavicular tumors; accordingly,orbital RMS has a significantly higher 5-year survival thanRMS at other head and neck sites (89% vs. 55%).74

On imaging, RMS is seen as a densely cellular infiltrating

FIGURE 41-32 Same patient as in Figure 41-30. MR images obtained 1 week after onset of neck pain. In A, aT1-weighted MR image, there is a poorly defined soft-tissue mass (arrow), while in B, a T2-weighted MR image, themass (arrow) has signal voids that could be interpreted as either vascular or fibrous in origin. There is alsoedematous-type high signal intensity in the immediate region. In C, a T2-weighted MR image more caudal in theneck, there is fullness and high signal intensity in the muscles and adjacent soft tissues (arrow). In D, a T2-weightedMR image obtained 1 month after onset, the mass and edema in the paraspinal muscles have decreased. This patienthad myositis ossificans.

41-26 NECK

neoplasm (Fig. 41-36). Skeletal muscle is always seen as thesite of origin. On both CT and MR imaging, masses aretypically homogeneous, with destruction of adjacent bone.Necrosis can be seen, but intratumoral hemorrhage isuncommon and calcification is typically absent. Tumor isisointense to muscle on T1-weighted images and hyperin-tense on T2-weighted images.142 Just over half of the casesenhance homogeneously, and the degree of enhancement issimilar to that of normal skeletal muscle. In most cases,tumor margins are poorly defined.

Metastasis to Muscle

Hematogenous metastasis to muscle is rare. The rela-tively low incidence may be related to muscle enzymeinhibitors, the acidic environment of muscle, or thevessel-squeezing effect of muscular contractions.143 Mostfrequently, the metastases come from primary tumors in thelung, colon, pancreas, breast, or kidney. Although pain,tenderness, and a mass are usually present, some suchmetastases may be clinically silent (Fig. 41-37).

THE STYLOHYOID SYNDROMES

Three dominant syndromes are related to the stylohyoidstructures: Eagle’s syndrome, styloid carotodynia, and hyoidfasciitis.

Eagle’s Syndrome

In 1937, Eagle described the elongated styloid processsyndrome, which consists of pharyngeal pain, referredotalgia, and a foreign body sensation in the throat occurringafter tonsillectomy. It is believed that this syndromedevelops because of fibrosis between the tonsillar fossa andan elongated styloid process; hence, the symptoms aregreatest during deglutition, phonation, and deep inspiration,when maximal pharyngeal movement occurs. Since the timeof its discovery, the term Eagle’s syndrome has come to beapplied to any patient who has these symptoms and anabnormally elongated styloid process. The normal styloidprocess may be as long as 2.5 cm. Thus, Eagle’s syndromemay be present whenever a longer styloid process is seen onimaging in a patient, whether or not there has been priortonsillectomy (Fig. 41-38). Complicating the picture evenmore is that some patients also have ossified stylohyoidligament(s), which can themselves fracture and becomesymptomatic.144 The treatment, if any, is surgical removal ofthe elongated styloid process(es).145–152 Because there aremany asymptomatic patients who have elongated styloidprocesses and/or ossified stylohyoid ligaments, some clini-cians question the validity of Eagle’s syndrome. Nonethe-less, in the symptomatic patient, shortening of the styloidprocess usually relieves the complaint. The presence of anelongated styloid process also makes this structure moreprone to injury during flexion-type trauma. The symptomsrelated to Eagle’s syndrome can also be confused with those

FIGURE 41-33 Axial cranial (A) and caudal (B) contrast-enhanced CT scans show fatty atrophy of virtually allof the muscles in the upper back and the floor of the posterior triangle. This patient had fascioscapulohumeraldystrophy.

Chapter 41 Skin and Soft-Tissue Lesions 41-27

attributed to a wide variety of facial neuralgias as well asoral, dental, and temporomandibular diseases.

Styloid Carotodynia

A related syndrome is styloid carotodynia, caused by anormal or elongated styloid process whose tip is deviated sothat it causes pressure on either the internal or externalcarotid arteries. This pressure causes stimulation of thepain-sensitive receptors found in the adventitia of thesevessels and results in pain along the vascular distribution ofthe affected vessel. When the internal carotid artery isaffected, pain occurs in the parietal and ophthalmic regionsand there is little or no pain below the level of the orbits.When the external carotid artery is involved, the pain is in

the ipsilateral face below the level of the orbit. Again,surgery is curative.

Hyoid Fasciitis

The least common of these syndromes is hyoid fasciitis,which is usually found in patients who have not had previousneck surgery. Pain and discomfort in the throat areexacerbated when the patient’s head is turned to the affectedside. The head turning stretches the muscles between thehyoid bone and the styloid process. Palpation of the neckelicits tenderness over the region of the hyoid bone. It isbelieved that this hyoid syndrome may be due to tendinitis/fasciitis of the muscular attachments (and of the attachmentof the stylohyoid ligament) to the hyoid bone. Someresearchers have proposed that certain patients with similar

FIGURE 41-34 Serial cranial (A) to caudal (C) contrast-enhanced CTscans show extensive fatty degeneration of the muscles of the back, floor ofthe posterior triangle, and right shoulder. This patient had fascioscapulo-humeral dystrophy.

41-28 NECK

FIGURE 41-35 Serial cranial (A) to caudal (C) contrast-enhanced CT scans show fatty degeneration of the sternocleidomas-toid and trapezius muscles and, to a lesser degree, the muscles of thefloor of the posterior triangle. There is also dilatation of the cervicalesophagus, and the patient has a tracheotomy tube. This patient hadmyotonic dystrophy.

FIGURE 41-36 Axial T1-weighted, contrast-enhanced MR image showsan enhancing, poorly defined mass arising in the paraspinal muscles of the leftneck. There is invasion of the left side of the vertebra. This patient had arhabdomyosarcoma. (Courtesy of Dr. Larissa Bilaniuk.)

symptoms may instead have a tenosynovitis of the interme-diate tendon of the digastric muscle.153 Treatment of hyoidfasciitis consists of local heat applied to the area and/orinjection of an anesthetic combined with corticosteroidsalong the affected greater horn(s). If these measures fail,relief may be difficult to achieve, as surgery is notconsidered a good option.154, 155

BLOOD VESSELS AND VASCULARVARIATIONS

Veins

There are usually at least three jugular veins on each sideof the neck. They are named by their position relative to thesternocleidomastoid muscle. Thus, there are the anteriorjugular, external jugular, and internal jugular veins. Ofthese, the internal jugular veins usually have the greatestvenous flow and thus are the largest vessels.

Asymmetry of the Internal Jugular VeinsThe internal jugular veins are almost always asymmetric,

with the right one being larger in nearly 80% of people. Inthe upper neck, the crowding of structures often preventspassive venous distention, and the asymmetry in the internaljugular veins appears minimal. However, more inferiorly theasymmetry is most notable, as the larger spaces of the neckallow more passive distention of the veins. The asymmetryis usually more evident on CT or MR imaging than it is

clinically. The disparity in the size of the veins can be sogreat as to cause the larger vein to be mistaken for a vascularmass. Tracing the course of the vein clarifies such a case.After a radical neck dissection, the shunting of venous bloodto the contralateral internal jugular vein can also causemassive enlargement of the vein (Fig. 41-39); this is anormal postoperative finding.

Multiple Jugular VeinsOccasionally, one or both of the internal jugular veins

may be multiple. In such cases, the more dorsal of the veinsis usually the smaller and may not enhance as well as thelarger ipsilateral vein on contrast-enhanced images. In theseinstances, on axial images the poorly enhanced vein may bemistaken for adenopathy. However, tracing the course of thevein will again clarify the situation.

The external jugular veins are even more variable thanthe internal jugular veins, and they may also be single ormultiple. Rarely, they can be larger than the ipsilateralinternal jugular vein. Similarly, the anterior jugular veins areusually asymmetric from side to side. These veins mostoften are seen along the anterior and medial margins of thesternocleidomastoid muscle. There is usually a small veinjust above the level of the manubrium that providescommunication between the two anterior jugular veins.Occasionally, this small vein may be severed during atracheotomy, causing a bloodied operative field. This smallvessel is rarely seen on CT or MR imaging.

PhlebectasiaPhlebectasia is an uncommon condition of the venous

system, possibly of a congenital etiology. Clinically,phlebectasia usually presents as a neck mass that enlargeswhen the patient performs a Valsalva maneuver, talks, orlies down. This normally asymptomatic mass decreases insize at rest or when the patient sits upright. When the internaljugular vein is affected, it presents as a cervical swelling thatcan mimic the signs of either a pharyngocele or alaryngocele. Because of its rarity, phlebectasia is frequentlymisdiagnosed.

In the neck, phlebectasia most often affects the internaljugular vein in both children and adults. However, almostany of the cervicofacial veins, such as the anterior jugularvein or the anterior facial vein, may also be affected. Usuallyno treatment is necessary for this benign condition, althoughsome authors have recommended surgical excision inselected asymptomatic patients for cosmetic and psycholog-ical purposes. Venography, anteriography, color Dopplersonography, and CT have previously been used to diagnosethis unusual condition.156–164

ThrombosisThrombosis of the jugular veins can occur secondary

to placement of a central line, placement of a porta-cath, infection, surgery, neoplasm, and intravenous drugabuse.165, 166 On CT, a thrombosed jugular vein is usuallyenlarged, and on contrast-enhanced images, an older clot isof lower attenuation than the normal vessel; enhancement ofthe vasa vasorum causes the vessel wall to be well seen. Ondynamic contrast-enhanced CT, a thrombus is usually lessdense than opacified blood. An acute clot may appear asdense as contrast-enhanced blood. In such a case, the clot is

FIGURE 41-37 Axial contrast-enhanced CT scan shows an enhancingmass in the right paraspinal muscles. This is a nonspecific imagingappearance. This patient had metastasis to the muscles from a primary lungcarcinoma.

41-30 NECK

FIGURE 41-38 Serial cranial (A) to caudal (C) contrast-enhanced CT scans show elongation of the styloidprocess bilaterally (arrows). The normal styloid process is less than 2.5 cm. These styloid processes were 3.5 cm.This patient, who complained of pain on swallowing, had Eagle’s syndrome. Coronal CT scan (D) on another patientwith Eagle’s syndrome shows bilaterally elongated styloid processes and ossification of the stylohyoid ligaments,virtually extending down to the hyoid bone.

FIGURE 41-39 Axial contrast-enhanced CT scan (A) shows a large but normal right internal jugular vein(arrow). In about 80% of patients, the right internal jugular vein is dominant. Axial contrast-enhanced CT scan (B)of a patient who has had a right radical neck dissection. The right internal jugular vein was resected, and the leftinternal jugular vein (arrow) has become enlarged.

better seen on either noncontrast images or delayed,contrast-enhanced scans as the vascular density decreases(Fig. 41-40). If inflammation is present, there will be afasciitis around the vein, with edema of the surrounding fatplanes. On MR imaging, jugular venous thrombosis may bemore difficult to detect because slow or turbulent flow maymimic a clot.

Lemierre’s syndrome is the association of an acutepharyngotonsillitis (which is an anaerobic oropharyngitis),septic thrombophlebitis of the ipsilateral internal jugularvein, and septicemia with septic emboli, most often to thelungs and large joints.167 There usually is an associatedregional reactive lymphadenitis (see Chapter 38).

Pseudocollateral and Collateral VeinsDue to the current rapid CT scan times and the rapid

injection of contrast with power injectors, contrast enhance-ment of collateral veins in the muscles of the neck and backmay become quite conspicuous (Fig. 41-41). Such opacifi-cation occurs even when the internal jugular vein is patentand well opacified. In such cases, visualization of theseveins does not necessarily imply thrombosis of the greatveins in the lower neck or superior mediastinum. However,when asymmetric posterior muscular collaterals are seen, itis usually prudent to check the lower neck and superiormediastinal veins on that side for the possibility ofthrombosis.

Condylar VeinThe vein of the condylar canal is a normal emissary

vein that exits the skull base through the posteriorcondylar canal.168 The condylar vein may be present on

one side or both sides, or it may be absent bilaterally.When bilateral, the two veins may be quite asymmetric insize. The importance of familiarity with the condylar veinlies in not mistaking it for lymphadenopathy or a mass(Fig. 41-42).

Arteries

Medial Deviation of the Internal Carotid ArteryThe internal carotid arteries are more consistently

symmetric than the jugular veins. Thrombosis and dissectionof the internal carotid artery are discussed further in Chapter40 and postoperative thrombosis of the internal carotidartery is shown in Chapter 45. The medial positioning of theinternal carotid artery(s) and, less frequently, of the carotidbulb may cause a bulge in the posterior pharyngeal wall; thisis shown in Chapter 40 and in Figure 41-43. Recognitionof this normal variant, and its inclusion in the writteninterpretation, will help to prevent potentially catastrophicbiopsy of the associated pharyngeal wall fullness.

An aneurysmal dilatation of an artery may also cause analtered course of the vessel that may mimic a mass in theneck. This is especially so in the lower neck (Fig. 41-44).

Aberrant Retroesophageal Right Subclavian ArteryAlthough an aberrant retroesophageal right subclavian ar-

tery may be an incidental observation on CT or MR studies,it occasionally may cause symptoms of dysphagia (dyspha-gia lusoria). A barium swallow shows the artery’s impres-sion on the right posterolateral wall of the esophagus, and thevessel can be seen on CT and MR studies (Fig. 41-45). An

FIGURE 41-40 Axial contrast-enhanced CT scan (A) shows athrombus in the right internal jugular vein. There is slight enhancementof the venous wall due to enhancement of the vasa vasorum. There is alsominimal effacement of the surrounding fat planes secondary to aphlebitis. Axial contrast-enhanced CT scan in another patient (B) showsa thrombus in the right internal jugular vein. The thrombus is lucent, andinflammation due to an associated phlebitis obscures the surrounding fatplanes.

41-32 NECK

aberrant right subclavian artery is associated with nonrecur-rence of the recurrent laryngeal nerve.

Thrombosis and DissectionDissections of the great arteries in the neck can be

spontaneous or related to blunt or penetrating trauma,strangulation, manipulation, angioplasty, infection, or intrin-sic disorders of the vessels such as collagen-vasculardisease.169–171 Approximately one fourth of patients withinternal carotid artery dissection will develop an associatedpseudoaneurysm.172 In a series of dissections related tomanipulation, vertebral artery involvement was four timesas frequent as carotid artery involvement; all vertebrallesions were seen around the atlantoaxial region, and 38%were bilateral.170

Imaging findings depend on the patient’s age at the timeof dissection and degree of resolution. On CT, fusiformnarrowing of the arterial contrast column is more reliablydemonstrated than actual subintimal hemorrhage. Theclassic MR appearance is that of a variably sized central flowvoid with a hyperintense rim or crescent on axial T1-weighted images, although this hyperintensity may not beseen in chronic cases (Fig. 41-46); conspicuity is augmentedby fat saturation. MR angiography may falsely represent thedegree of vascular compromise due to changes in flow ratethrough the dissection; the addition of contrast may help tobetter define the residual lumen.

AneurysmAneurysms of the cervical internal carotid artery are rare

lesions that typically present as pulsatile cervical masses. Aseries of 38 cases demonstrated relatively common associa-

FIGURE 41-41 Axial contrast-enhanced CT scan (A) on a normal patient shows intense enhancement of themuscular vessels of the posterior neck (arrows). Although this could be seen in a patient with venous obstruction,there was no such obstruction and these were not collateral vessels. The contrast was administered by rapid injection,and the patient was scanned during contrast administration (1 second per scan). The vessels are probably veinsopacified by reflux from the internal jugular vein (note the asymmetry of jugular opacity). Axial contrast-enhancedCT scan (B) shows a lucent thrombus in the left internal jugular vein and enhancement of the vein wall due tocontrast in the vasa vasorum. There are also numerous large collateral venous channels (arrows) in the lateral andposterior left neck.

FIGURE 41-42 Axial T1-weighted image through the level of theforamen magnum shows a condylar vein with high signal intensity on eachside of the neck (arrows). Asymmetry of the condylar veins is normal, andthe high signal intensity reflects slow or turbulent venous flow. Theimportance of the condylar veins lies in their not being mistaken forabnormal lymph nodes.

Chapter 41 Skin and Soft-Tissue Lesions 41-33

tions with atherosclerosis, fibromuscular disease, dissection,and trauma.173 These aneurysms tend to arise in the distalthird of the cervical internal carotid artery, and pseudoaneu-rysms are more common than true aneurysms.174 Onimaging, there is intense enhancement. Since there may besignificant flow-related signal loss within the aneurysmitself on MR imaging, the lumen may be better appreciatedon contrast-enhanced CT (Fig. 41-44).

Hemangioma

Cutaneous hemangiomas are the most common tumors ofinfancy and childhood; pathologically, they are classified asinfantile, capillary, or cellular. These tumors have acharacteristic clinical course that consists of rapid postnatalgrowth (proliferating phase), slow, spontaneous regression(involuting phase), and finally, restoration of either normalor altered skin (involuted phase).175 Pathologically similarlesions occur in adults, although these lesions do notspontaneously involute. Despite the difference in clinicalbehavior, most pathologists still tend to refer to all of theselesions as hemangiomas. However, there is an alternativeclinical/pathologic classification that restricts the termhemangioma to the typical lesion described above, withonset in the infant or child. The pathologically similar lesionthat has its onset in adults is referred to as a vascularmalformation.175 In addition, a variety of other vascularmalformations occur in adults, which are classified by thedominant vessel (i.e., venous, arteriovenous, or arterial).The imaging of hemangiomas is described in variouschapters in this book.

Hemangiopericytoma

Hemangiopericytomas are unusual tumors of vascularorigin that usually present as painless masses. Approxi-mately one in six tumors arise in the head and neck region,less frequently than those seen in the trunk, pelvis/retroperitoneum, and extremities. Males and females areaffected equally, and the peak incidence is near themid-fourth decade, although there is a wide age range atpresentation (first through seventh decades).176 Thesmall percentage of these tumors seen in the neonatalperiod tend to be more benign, with some maturing tohemangiomas.177

Benign hemangiopericytomas are characterized histolog-ically by branched vessels lined with normal epithelial cellsand surrounded by a connective tissue matrix. Features ofmalignant transformation include increased mitoses, irregu-lar or unusual vascular spaces, and proliferation ofconnective tissue; necrosis and hemorrhage do not appear tobe common. Up to half of even benign-appearing tumorsmay recur, and wide local excision is recommended.Patients should be monitored carefully for delayed recur-rences, which may be seen a decade or more after initialtumor excision.176

The majority of tumors arise in extramucosal sites.178

The location of the tumor adds prognostic value, sincesoft-tissue tumors are more likely than mucosal tumors torecur locally and metastasize.176 The utility of radiationtherapy has been questioned, and its use may be limited totumors with positive margins, high-grade tumors, andrecurrences.178 The tumor may be embolized preoperativelyto minimize blood loss, although many surgeons first use

FIGURE 41-43 Axial contrast-enhanced CT scan (A) shows a normal variant, a medially displaced right carotidbulb indenting the posterior wall of the hypopharynx. The left carotid bulb, which has calcific atheroscleroticchanges, is seen more laterally relative to the pharynx on the opposite side. Axial T1-weighted MR image of anotherpatient (B) shows an almost midline-deviated right internal carotid artery (arrow). (Courtesy of Dr. David W.Johnson.)

41-34 NECK