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is a pathologic cavity filled with fluid,by epithelium, and surrounded by a def-

inite connective tissue wall. The cystic fluid either issecreted by the cells lining the cavity or derives fromthe surrounding tissue fluid.

PERI PH ERY

Cysts that originate in bone usually have a peripherythat is well defined and corticated (characterized by afairly uniform, thin, radiopaque line). However, a sec-ondary infection or a chronic state can change thisappearance into a thicker, more sclerotic boundary. .

Clinical FeaturesCysts occur more often in the jaws than in any otherbone because most cysts originate from the numerousrests of odontogenic epithelium that remain after toothformation. Cysts are radiolucent lesions, and the preva-lent clinical features are swelling, lack of pain (unlessthe cyst becomes secondarily infected or is related to anonvital tooth), and missing teeth, especially thirdmolars.

SHAPE " ...

Cysts usually are round or oval, resembling a fluid-filledballoon. Some cysts may have a scalloped boundary.

INTERNAL STRUCTURE

Cysts often are totally radiolucent. However, long-stand-ing cysts may have dystrophic calcification, which cangive the internal aspect a sparse, particulate appear-ance. Some cysts have septa, which produce multipleloculations separated by these bony walls or septa. Cyststhat have a scalloped periphery may appear to havein ternal septa. Occasionally the image of structures thatare positioned on either side of the cyst may overlap theinternal aspect of the cyst, giving the false impressionof internal structure.

EFFECTS ON SURROUNDINGSTRUCTURES

Cysts grow slowly, sometimes'.causing displacement andresorption of teeth. The aria 01toOth resorption oftenhas a sharp, curved shape. ..Cysts can expand the

384

LOCATIONCysts may occur centrally (within bone) in any loca-tion in the maxilla or mandible but are rare in thecondyle and coronoid process. Odont4.>genic cystsare found most often in the tooth~bearirig region.In the mandible, they originate above ..the' inferioralveolar nerve canal. Odontogenic cysts n1ay growinto the maxillary antrum. Some nonodontogeniccysts also originate within the antrum (see Chapter 26).A few cysts arise in the soft tissues of the orofacial

region.

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CHAPTER 20 CYSTS OF THE JAWS 385

mandible, usually in a smooth, curved manner, andchange the buccal or lingual cortical plate into a thincortical boundary. Cysts may displace the inferior alve-olar nerve canal in an inferior direction or invaginatethe maxillary antrum, maintaining a thin layer of bonethat separates the internal aspect of the cyst from ,t4~;.;antrum.

swelling. On palpation the swelling may feel bonyand hard if the cortex is intact, crepitant as the bonethins, and rubbery and fluctuant if the outer cortexis lost. The incidence of radicular cysts is greater inthe third to sixth decades and shows a slight malepredominance.

Radiographic FeaturesLocation. In most cases the epicenter of a radicular cyst

-is located approximately at the apex of a nonvital tooth(Fig. 20-1). Occasionally it appears on the mesial ordistal surface of a tooth root, at the opening of an ac-cessory canal, or infrequently in a deep periodontalpocket. Most radicular cysts (60%) are found in themaxilla, especially around incisors and canines.Because of the distal inclination of the root, cysts thatarise from the maxillary lateral incisor may invaginatethe antrum. Radicular cysts may also form in relationto a nonvital deciduous molar and be positioned buccalto the developing bicuspid.

RADICULAR CYST

SynonymsPeriapical cyst, apical periodontal cyst, or dental cyst

DefinitionA radicular cyst is a cyst that most likely results whenrests of epithelial cells (Malassez) in the periodontalligament are stimulated to proliferate and undergocystic degeneration by inflammatory products from anonvital tooth.

Periphery and shape. The periphery usually has a well-defined cortical border (Fig. 20-2). If the cyst becomessecondarily infected, the inflammatory reaction of thesurrounding bone may result in loss of this cortex (seeFig. 20-1, B) or alteration of the cortex into a more scle-rotic border. The outline of a radicular cyst usually iscurved or circular unless it is influenced by surround-ing structures such as cortical boundaries.

Clinical FeaturesRadicular cysts are the most common type of cyst inthe jaws. They arise from nonvital teeth (i.e., teeth thathave lost vitality because of extensive caries, largerestorations, or previous trauma). Often radicularcysts produce no symptoms unless secondary infec-tion occurs. A cyst that becomes large may cause

A tj

FIG. 20-1 Radicular cysts. In A, note that the epicenter is apical to the lateral incisorand the presence of a peripheral cortex (arrows). In B, note the lack of a well-definedperipheral cortex as this cyst was secondarily infected and that the root canal of the lateralincisor is abnormally wide as it is visible at the root apex.


,386 PART V RADIOGRAPHIC INTERPRETATION OF PATHOLOGY

cent teeth may occur. The resorption pattern may havea curved outline. In rare cases the cyst may resorb theroots of the relatednonvital tooth. The cyst may invagi-nate the antrum, but there should be evidence of a cor-tical boundary between the contents of the cyst and theinternal structure of the antrum. The outer corticalplates of the maxilla or mandible may expand in acurved or circular shape (Fig. 20-3). Cysts may displacethe mandibular alveolar nerve canal in an inferiordirection.

Internal structure. In most cases the internal structureof radicular cysts is radiolucent. Occasionally, dystro-phic calcification may develop in long-standing cysts,appearing as sparsely distributed, small particulate

radiopacities., "FiJi

Effects on surrounding structures. If a radicttlar cyst islarge, displacement and resorption of the roots of adja-

Differential DiagnosisDifferentiation of a small radicular cyst from an apicalgranuloma may be difficult and in some cases im-possible. A round shape, a well-defined cortical border,and a size greater than 2 cm in diameter are morecharacteristic of a cyst. An early radiolucent stage ofperiapical cemental dysplasia, a radiolucent apicalscar, and a periapical surgical defect should also beconsidered in the differential diagnosis. The patient'shistory helps with the differentiation. Radicular cyststhat originate from the maxillary lateral incisor andare positioned between the roots of the lateral incisorand the cuspid may be difficult to differentiate froman odontogenic keratocyst or a lateral periodontalcyst. The vitality of the involved tooth should be tested.A nonvital tooth may have a larger pulp chamberthan neighboring teeth because of the lack of sec-ondary dentin, which normally forms with time inthe pulp chamber and canal of a vital tooth (seeFig. 20-1).

FIG. 20-2 A periapical tilm ot a radicular cyst reveals alesion with a well-defined cortical boundary (arrows). Notethat the presence of the inferior cortex of the mandible hasinfluenced the circular shape of the cyst.

A D

FIG. 20-3 A ~nd B, Two im~ges of a radicular cyst originating from a nonvital decidu-ous second molar show expansion of the buccal cortical plate to a circular or hydraulicshape (arrows) and displacement of the adjacent permanent teeth.


387CYSTS OF THE JAWSCHAPTER 20

FIG. 20-4 Axial (A) and coronal (8) CT images using bone algorithm of a collapsingradicular cyst within the sinus. Note the unusual shape and the fact that new bone (arrows)is being formed from the periphery (arrows) toward the center. (Courtesy of Drs. S. Ahingand T. Blight, University of Manitoba.)

A large radicular cyst that has invaginated the max-illary antrum may collapse and start filling in with newbone (Fig. 20-4). With biopsy, the histologic analysismay result in an erroneous diagnosis of ossifyingfibroma or a benign fibroosseous lesion. Radiographi-cally, the important feature is that the new bone alwaysforms first at the periphery of the cyst wall as the cystshrinks and not in the center of the cyst; this is a dif-ferent pattern of bone formation than is seen withbenign fibroosseous lesions.

ManagementTreatment of a tooth with a radicular cyst may includeextraction, endodontic therapy, and apical surgery.Treatment ofa large radicular cyst usually involves sur-gical removal or marsupialization. The radiographicappearance of the periapical area of an endodonticallytreated tooth should be checked periodically to makesure that normal healing is occurring (Fig. 20-5). Char-acteristically, new bone grows into the defect from theperiphery, sometimes resulting in a radiating patternresembling the spokes of a wheel. However, in a fewcases normal bone may not fill the defect, especially ifa secondary infection or a considerable amount of bonedestruction occurred. Recurrence of a radicular cyst isunlikely if it has been removed completely.

FIG. 20-5 A radicular cyst that is healing after endodon-tic treatment. Arrows show the original outline of the cyst;note that the new bone grows toward the center from the

periphery.

most often for a radicular cyst that may be left behindmost commonly after extraction of a tooth.

Clinical FeaturesA residual cyst usually is asymptomatic and often is dis-covered on radiographic examination of an edentulousarea. However, there may be some expansion of the jawor pain in the case of secondary infection.

RESIDUAL CYST

DefinitionA residual cyst is a cyst that remains after incompleteremoval of the original cyst. The term residual is used


388 PART V RADIOGRAPHIC INTERPRETATION OF PATHOI O~Y

Radiographic FeaturesLocation. Residual cysts occur in both jaws, althoughthey are .found slightly more often in the mandible. Theepicenter is positioned in a periapical location. In themandible the epicenter is always above the inferior alve-olar nerve canal (Fig. 20-6). '

ManagementThe treatment for residual cysts is surgical removal ormarsupialization, or both, if the cyst is large.

Periphery and shape. A residual cyst has a corticalmargin unless it becomes secondarily infected. Its shapei~ OV:I.1 or rirclIl:lr.

DENTIGEROUS CYST

SynonymFolli(,lll~r rv"t

DefinitionA dentigerous cyst is a cyst that forms around the crownof an unerupted tooth. It begins when .fluid accumu-lates in the layers of reduced enamel epithelium orbetween the epithelium and the crown of theunerupted tooth. An eruption cyst is the soft tissuecounterpart of a dentigerous cyst.

Internal structure. The internal aspect of a residual cysttypically is radiolucent. Dystrophic calcifications may bepresent in long-standing cysts.

Effects on surrounding structures. Residual cysts cancause tooth displacement or resorption. The outer cor-tical plates of the jaws may expand. The cyst may invagi-nate the maxillary antrum or depress the inferioralveolar nerve canal.

Clinical FeaturesDentigerous cysts are the second most common type ofcyst. in the jaws. They develop around the crown of anunerupted or supernumerary tooth. The clinical exam-ination reveals a missing tooth or teeth and possibly ahard swelling, occasionally resulting in facial asymme-try. The~pa6ent typically has no pain or discomfort.About 4% of individuals with at least one uneruptedtooth have a dentigerous cyst. Dentigerous cysts aroundsupernumerary teeth account for about 5% of alldentigerous cysts, most developing around a mesiodensin the anterior maxilla.

Differential DiagnosisWithout the patient's history and previous radiographs,the clinician may have difficulty determining whethera solitary cyst in the jaws is a residual cyst. Other ex-amples of common solitary cysts include odontogenickeratocysts. A residual cyst has greater potential forexpansion compared with an odontogenic keratocyst.The epicenter of a Stafne developmental salivary glanddefect is located below the mandibular canal (and thusis unlikely to be odontogenic in nature). Radiographic Features

Location. The epicenter of a dentigerous cyst is foundjust above the crown of the involved tooth, whichusually is tpe mandibular or maxillary third molar orthe maxillary canine, the teeth most commonly affected(Fig. 20-7). An important diagnostic point is that thiscyst attaches at the cementoenamel junction. Somedentigerous cysts are eccentric, developing from thelateral aspect of the follicle so that they occupy an areabeside the crown instead of above the crown (see Fig.20-7, D). Cysts related to maxillary third molars oftengrow into the maxillary antrum and may become quitelarge before they are discovered. Cysts attached to thecrown of mandibular molars may extend a considerabledistance into the ramus.

Periphery and shape. Dentigerous cysts typicallyhave a well-defined cortex with a curved or circularoutline. If infection is present, the cortex may be

missing.FIG. 20-6 The epicenter of this infected residual cyst isabove the inferior alveolar nerve canal and has displaced thecanal in an inferior direction (arrows). Note that the corticalboundary is not continuous around the whole cyst.

Internal structure. The internal aspect is completelyradiolucent except for the crown of the involvedtooth.


,CHAPTER 20 389CYSTS OF THE JAWS

BA


,390 PART V RADIOGRAPHIC INTERPRETATION OF PATHOLOGY

Effects on surrounding structures. A dentigerous cysthas a propensity to displace and resorb adjacent,teeth(Fig. 20-8). It commonly displaces the associated toothin an apical direction (Fig. 20-9). The degree of dis-placement may be considerable. For instance, maxillarythird molars or cuspids may be pushed to the 'floor ofthe orbit (see Fig. 20-8), and mandibular third molarsmay be moved to the condylar or coronoid regions orto the inferior cortex of the mandible (Fig. 20-10). Thefloor of the maxillary antrum may be displaced as the-cyst invaginates the antrum, and the cyst may displacethe inferior alveolar nerve canal in an inferior direc-tion. This slow-growing cyst often expands the outercortical boundary of the involved jaw.

Differential DiagnosisBecause the histopathologic app~arance of the liningepithelium is not specific, the diagnosis relies on theradiographic and surgical observation of the attach-ment of the cyst to the cementoenamel junction. Ahistopathologic examination must always be done toeliminate other possible lesions in this location.

One of the most difficult differential diagnoses tomake is between a small dentigerous cyst and a hyp~r-plastic follicle. A cyst should be considered with anyevi-dence of tooth displacement or considerable expansionof the involved bone. The size of the normal follicularspace is 2 to 3 mm. If the follicular space exceeds 5 mm,a dentigerous cyst is more likely. If uncertainty remains,

l,;t:S

1-1\.1. ~U-B A, I nls panoramic Image reveals lne presence OT a large aenugerous CYSlassociated with the left maxillary cuspid (arrow), which has been displaced. Notice the dis-placement and resorption of other teeth in the left maxilla. Band C, Coronal and axial CTimages of the same case showing superior-lateral displacement of the cuspid, expansionof the anterior wall of the maxilla and expansion of the cyst into the nasal fossa.


-A

--""""~ -' ""-" """"'""-".B

FIG. 20-9 A and B, These panoramic films of the same case taken several years apartdemonstrate superior-posterior displacement of a maxillary third molar by a dentigerous cyst.

BA

Dc -~~-

FIG. 20-10 Dentigerous cysts displacing teeth. A, The third molar has been displacedto the inferior cortex. 8, The second molar has been displaced into the ramus by a cystassociated with the first molar. Axial (C) and coronal (D) CT images using bone algorithmreveal a maxillary third molar displaced into the space occupied by the maxillary antrum.


392 PART V RADIOGRAPHIC INTERPRETATION OF PATHOLOGY

It is unclear whether the paradental cyst of the thirdmolar and the buccal bifurcation cyst (associated withfirst and second molars) are the same entity. The buccalbifurcation cyst (BBC) is certainly a distinct clinicalentity. An associated enamel extension into the furca-tion region of third molars with paradental cysts has notbeen documented with molars involved in a BBC. Also,the inflammatory component associated with paraden-tal cysts is not always present with BBCs.

the region should be reexamined in 4 to 6 months todetect any increase in size or any influence on sur-rounding structures characteristic of cysts.

The differential diagnosis also may include an odon-togenic keratocyst, an ameloblastic fibroma, and a cysticameloblastoma. An odontogenic keratocyst ,~ notexpand the bone to the same degree as a dentigerouscyst, is less likely to resorb teeth, and may attach fartherapically on the root instead of at the cementoenameljunction. It may not be possible to differentiate a smallameloblastjc fibroma or cystic ameloblastoma from adentigerous cyst if there is no internal structure. Otherrare lesions that may have a similar pericoronal ap-pearance are adenomatoid odontogenic tumors andcalcified odontogenic cysts, both of which can sur-round the crown and root of the involved tooth.Evidence of a radiopaque internal structure shouldbe sought in these two lesions. Occasionally a radicularcyst at the apex of a primary tooth surrounds the crownof the developing permanent tooth positioned apicalto it, giving the false impression of a dentigerous cystassociated with the permanent tooth. This occursmost often with the mandibular deciduous molarsand the developing bicuspids. In these cases the clini-cian should look for deep caries or extensive res-torations in a primary tooth that would indicate aradicular cyst.

Clinical FeaturesA common sign is the lack of or a delay in eruption ofa mandibular first or second molar. On clinical exami-nation the molar may be missing or the lingual cusp tipsmay be abnormally protruding through the mucosa,higher than the position of the buccal cusps. The firstmolar is involved more frequently than the secondmolar. The teeth are always vital. A hard swelling maybe present buccal to the involved molar, and if it is sec-ondarily infected, the patient has pain. The age ofdetection is younger, within the first 2 decades for aBBC and in the third decade for a paradental cyst ofthe third molar.

Radiographic FeaturesLocation. The mandibular first molar is the mostcommon location of a BBC, followed by the secondmolar. The cyst occasionally is bilateral. It is alwayslocated in the buccal furcation of the affected molar(Fig. 20-11). On periapical and panoramic films thelesion may appear to be centered a littl~ distal to thefurcation of the involved tooth.

ManagementDentigerous cysts are treated by surgical removal, whichmay include the tooth as well. Large cysts may betreated by marsupialization before removal. The cystlining should be submitted for histologic examinationbecause ameloblastomas have been reported to occurin the cyst lining. In addition, squamous cell carcinomahas been reported to arise from the cyst lining of chron-ically infected cysts. Mucoepidermoid carcinoma alsohas been reported.

Periphery and shape. In some cases the periphery is notreadily apparent, and the lesion may be a very subtleradiolucent region superimposed over the image of theroots of the molar. In other cases the lesion has a cir-cular shape with a well-defined cortical border. Somecysts can become quite large before they are detected.

Internal structure. The internal structure is radiolucent.

Effects on surrounding structures. The most strikingdiagnostic characteristic of a BBC is the tipping of theinvolved molar so that the root tips are pushed into thelingual cortical plate of the mandible (see Fig. 20-11, Band C) and the occlusal surface is tipped toward thebuccal aspe<;! of the mandible (see Fig. 20-11, A). Thisaccounts for'the lingual cusp tips being positionedhigher than the buccal tips. This tipping may bedetected in a panoramic or periapical film if the imageof the occlusal surface of the affected tooth is apparent,whereas the unaffected teeth are not. The best diag-nostic film is the cross-sectional (standard) mandibular

BUCCAL BIFURCATION CYST

SynonymsMandibular infected buccal cyst, paradental cyst, orinflammatory collateral dental cyst

DefinitionThe source of epithelium probably is the epithelialcell rests in the periodontal membrane of the buccalbifurcation of mandibular molars. The histopathologiccharacteristics of the lining are not distinctive. The etio-logy of proliferation is unknown; one theory holdsthat inflammation is the stimulus, but inflammation isnot always present. The World Health Organization.includes these cysts under inflammatory cysts.


393CHAPTER 20 CYSTS OF THE JAWS

A

B CFIG. 20-11 Bilateral buccal bifurcation cysts. A, A panoramic image showing cystsrelated to the mandibular first molars. Note that the occlusal surface of each tooth hasbeen tipped in relation to the other teeth and that adjacent teeth have been displaced.Band C, Occlusal films of the same case. Note the circular expansion of the buccal cortexand the displacement of the roots of the first molars into the lingual cortical plate (arrows).

occlusal projection, which demonstrates the abnormalposition of the root apex. If the cyst is large enough, itmay displace and resorb the adjacent teeth and cause aconsiderable amount of smooth expansion of thebuccal cortical plate. If the cyst is secondarily infected,periosteal new bone formation is seen on the buccalcortex adjacent to the involved tooth.

However, the epicenter of a dentigerous cyst is differ-ent because a BBC starts near the bifurcation region ofthe tooth and does not surround the crown, as does a

dentigerous cyst.

ManagementA BBC usually ~s removed by conservative curettage,although some c~es have resolved without interven-tion. The involved ~olar should not be removed. BBCsdo not recur.

Differential DiagnosisDiagnosis of a BBC relies entirely on clinical and radi-ographic information. The major differential diagnosisincludes lesions that could elicit an inflammatoryperiosteal response on the buccal aspect of mandibularmolars such as a periodontal abscess or Langerhans'cell histiocytosis. The fact that only a BBC tilts the molaras described helps to differentiate it from other lesions.Also in the differential diagnosis is the dentigerous cyst.

ODONTOGENIC KERATOCYST

SynonymIt is a commonly held view that primordial cysts areodontogenic keratocysts. However, this view is not uni-versally accepted.


394 I'AK I V KAUIUl.KAI'HIL INIt.KI'Kt.IAIIUN UI- I'AIHULUlJY

or tragments ot epithelium left behind alter surgicalremoval of the cyst.

DefinitionAn odontogenic keratocyst (OKC) is a noninflamma-tory odontogenic cyst that arises from the dentallamina. Unlike other cysts, which are thought to growsolely by osmotic pressure, the epithelium in an OKCappears to have innate growth potential, much as in'..,abenign tumor. This difference in the mechanism~ ofgrowth gives OKCs a different radiographic appear-ance. The epithelial lining is distinctive because it is ker-atinized (hence the name) and thin (4 to 8 cells thick).Occasionally bvdlike proliferations of epithelium growfrom thtt basal layer into the adjacent connective tissuewall. Also, islands of epithelium in the wall may give riseto satellite microcysts. The inside of the cyst often con-tains a viscous or cheesy material derived from the

epithelial lining.

Radiographic FeaturesLocation. The most common location of an OKC is theposterior body of the mandible (90% occur posteriorto the canines) and ramus (more than 50%) (Fig. 20-12). The epicenter is located superior to the inferioralveolar nerve canal. This type of cyst occasionally hasthe same pericoronal position as, and is indistinguish-able from, a dentigerous cyst (see Fig. 20-12).

Periphery and shape. As with other cysts, OKCs usuallyshow evidence of a cortical border unless they havebecome secondarily infected. The cyst may have asmooth round or oval shape identical to that of othercysts, or it may have a scalloped outline (a series of con-tiguous arcs) (see Figs. 20-12 and 20-14, C).Clinical Features

OKCs account for about one tenth of all cysts in thejaws. They occur in a wide age range, but most developduring the second and third decades, with a slight malepredominance. The cysts sometimes form around anunerupted tooth. OKCs usually have no symptoms,although mild swelling may occur. Pain may occur withsecondary infection. Aspiration may reveal a thick,yellow, cheesy material (keratin). It is important to notethat, unlike other cysts, OKCs have a high propensityfor recurrence, possibly because of small satellite cysts

Internal structure. The internal structure most com-monly is radiolucent. The presence of internal keratindoes not increase the radiopacity. In some cases curvedinternal septa may be present, giving the lesion a mul-tilocular appearance (Fig. 20-13; see also Fig. 20-12).

tttects on surrounding structures. An important char-acteristic of the OKC is its propensity to grow along theinternal aspect of the jaws, causing minimal expansion

~ ...FIG. 20-12 A, Panoramic image shows a large keratocyst occupying the ramus andbody of the mandible; note the septa (black arrow), inferiorly displaced mandibular canal(white arrow), and the root resorption. The keratocyst in B has a pericoronal position rel-ative to the impacted third molar and the distal margin has a scalloped shape.


CHAPTER 20 395CYSTS OF THE JAWS

B cFIG. 20-13 A, Cropped panoramic image of a keratocyst occupying the mandibularramus; note the septa (arrow). 8 and C, Axial CT images using bone algorithm of the samecase demonstrating very little expansion in the body (8) but significant expansion in theupper ramus in C (arrows).

(Fig. 20-14). This occurs throughout the mandibleexcept for the upper ramus and coronoid process,where considerable expansion may occur (see Fig. 20-13, C). Occasionally the expansion of large cysts mayexceed the ability of the periosteum to form new bone,thus allowing the cyst wall to contact soft tissue periph-eral to the outer cortex of the mandible (Fig. 20-15).The relatively slight expansion common with these cystsprobably contributes to their late detection, which occa-sionally allows them to reach a large size. OKCs can dis-place and resorb teeth but to a slightly lesser degreethan dentigerous cysts. The inferior alveolar nerve

canal may be displaced inferiorly. In the maxilla this cystcan invaginate and occupy the entire maxillary antrum.

Differential DiagnosisWhen in a pericoronal position, an OKC may be indis-tinguishable from a dentigerous cyst. The cyst is likelyto be an OKC if the cyst is connected to the tooth at apoint apical to the cementoenamel junction or if noexpansion of the cortical plates has occurred. Thetypical scalloped margin and multilocular appearanceof the OKC may resemble an ameloblastoma, but thelatter has a greater propensity to expand. An OKC may



A B

CFIG. 20-14 A large keratocyst occupying most of the right body and ramus of themandible. A, Note that, despite the cyst's size, the buccal and lingual cortical plates of themandible have expanded only slightly, as can be seen in the occlusal film (8). C, An axialimage of a keratocyst within the body of the mandible; note the lack of expansion and thecyst sc~lloping between the roots of the teeth.

show some similarity to an odontogenic myxoma, espe-cially in the characteristics of mild expansion and mul-tilocular appearance. A simple bone cyst often has ascalloped margin and minimal bone expansion, as withan OKC; however, the margins of a simple bone cystusually are more delicate and often difficult to detect.If several OKCs are found (which occurs in 4% to 5%of cases), these cysts may constitute part of a basal cellnevus syndrome.

this cyst has a propensity to recur, an accurate deter-mination of the extent and location of any cortical per-forations with soft tissue extension is best achieved withcomputed tomography. In the case of multiple cysts andthe possibility of basal cell nevus syndrome, a thoroughradiologic examination is required. This allows accuratedetermination of the number of cysts and other osseouscharacteristics that confirm the diagnosis.

Surgical treatment may vary and can include resec-tion, curettage, or marsupialization to reduce the sizeof large cysts before surgical excision. More attentionusually is devoted to complete removal of the walls ofthe cyst to reduce the chance of recurrence. Mter sur-

ManagementIf an OKC is suspected, referral to a radiologist for acomplete radiologic examination is advisable. Because



A BFIG. 20-15 A, Cropped panoram1c image revealing a large keratocyst occupying mostof the ramus; note the scalloping margin (arrows). 8, This axial CT using soft tissue windowof the same case showing perforation of the medial cortex and contacting the medial ptery-goid muscle (arrow).

gical treatment, it is important to make periodic posttreatment clinical and radiographic examinations todetect any recurrence. Recurrent lesions usuallydevelop within the first 5 years but may be delayed aslong as 10 years.

Clinical FeaturesBasal cell nevus syndrome starts to appear early in life,usually after 5 years of age and before 30 years of age,with the development of jaw cysts and skin basal cell car-cinomas. The lesions occur as multiple OKCs of thejaws, usually appearing in multiple quadrants andearlier in life than solitary OKCs. The recurrence rateof OKCs in this syndrome appears to be higher thanwith the solitary variety. The skin lesions are small, flat-tened, flesh-<:olored or brown papules that can occuranywhere on the body but are especially prominent onthe face, neck, and trunk. Occasionally basal cell carci-nomas form later in life than the jaw cysts or not at all.Skeletal anomalies include bifid rib (most common)and other costal abnormalities such as agenesis, defor-mity, and synostosis of the ribs, kyphoscoliosis, vertebralfusion, polydactyly, shortening of the metacarpals, tem-poral and temporoparietal bossing, minor hyper-telorism, and mild prognathism. Calcification of the

BASAL CEll NEVUS SYNDROME

SynonymsNevoid basal cell carcinoma syndrome or Gorlin-Goltz

syndrome

DefinitionThe term basal cell nevus syndrome comprises a numberof abnormalities such as multiple nevoid basal cell car-cinomas of the skin, skeletal abnormalities, centralnervous system abnormalities, eye abnormalities, andmultiple OKCs. It is inherited as an autosomal domi-nant trait with variable expressivity.


~9R DADT V RADIOC;RAPHIC INTFRPRFTATION OF PATHOlor;'

falx cere brio and other parts of the dura occur early inI;fp

screening film. Referral for genetic counseling may beappropriate.

Radiographic FeaturesLocation. The location is the same as that of solitaryOKCs, as described previously. The multiple keratocystsmay develop bilaterally and can vary in size from 1 mmto several centimeters in diameter (Fig. 20-16).

LATERAL PERIODONTAL CYST

DefinitionLateral periodontal cysts are thought to arise fromepithelial rests in periodontium lateral to the toothroot. This condition usually is unicystic, but it mayappear as a cluster of small cysts, a condition referredto as botryoid odontogenic cysts. It has been postulatedthat the lateral periodontal cyst is the intrabony coun-terpart of the gingival cyst in the adult.

Other radiographic features. See the preceding radi-ographic .description of ORCs. In addition, aradiopaque line of the calcified falx cerebri may beprominent on the posteroanterior skull projection.Occasionally this calcification may appear laminated.

Clinical FeaturesThe lesions usually are asymptomatic and less than 1 cmin diameter. The disorder has no apparent sexualpredilection, and the age distribution extends from thesecond to the ninth decades (the mean age is about 50years). If these cysts become secondarily infected, theywill mimic a lateral periodontal abscess.

Differential DiagnosisThe presence of a cortical boundary and other cysticcharacteristics differentiate basal cell nevus syndromefrom other abnormalities characterized by multipleradiolucencies (e.g., multiple myeloma). Cherubismappear.s as bilateral multilocular lesions but usually hassignificant jaw expansion, which is not characteristicof basal cell nevus syndrome. Also, cherubism pushesposterior teeth in an anterior direction, a distinctivecharacteristic. Occasionally patients ~with multipledentigerous cysts may show some similarities, butdenti~erous cysts are more expansile.

Radiographic FeaturesLocation. Fifty percent to 75% of lateral periodontalcysts develop in the mandible, mostly in a regionextending from the lateral incisor to the second pre-molar (Fig. 20-17).

Occasionally these cysts appear in the maxilla, espe-cially between the lateral incisor and the cuspid.Management

The keratocysts are treated more aggressively thanother solitary OKCs because there appears to be aneven greater propensity for recurrence. It is reason-able to examine the patient yearly for new and recur-rent cysts. A panoramic film serves as an adequate

Periphery and shape. A lateral periodontal cyst appearsas a well-defined radiolucency with a prominent corti-cal boundary and a round or oval shape. Rare largecvsts have a more irregular shaDe.

FIG. 20-16 Multiple OKCs associated with nevoid basal cell carcinoma syndrome.A, Upper arrows point to opacified maxillary antra; smaller arrow indicates the extensionof one of the mandibular cysts (lower arrows) into the bifurcation region of a mandibularmolar. B, Five cysts are present, which are related to the mandibular third molars and leftcuspid and to the maxillary left second premolar and third molar.


,399CYSTS OF THE JAWSCHAPTER 20

A BFIG. 20-17 Lateral periodontal cysts in the mandibular premolar region. B has theclassic well-defined cortical border, whereas A does not.

Internal structure. The internal aspect usually is radi-olucent. The botryoid variety may have a multilocular

appearance.

DefinitionCalcifying odontogenic cysts are uncommon, slow-growing, benign lesions. They occupy a spectrumranging from a cyst to an odontogenic tumor, withcharacteristics of a cyst alone or sometimes thoseof a solid neoplasm (epithelial proliferation and a ten-dency to continue growing). The World Health Orga-nization now categorizes calcifying odontogenic cysts asbenign tumors. Tfii~ lesion may manufacture calcifiedtissue identified as dysplastic dentin, and in someinstances the lesion is associated with an odontoma.This lesion also sometimes contains a more solid com-ponent that gives it an appearance resembling anameloblastoma, although it does not behave likeone.

Effects on surrounding structures. Small cysts mayefface the lamina dura of the adjacent root. Large cystscan displace adjacent teeth and cause expansion.

Differential DiagnosisBecause the location and radiographic appearance of alateral periodontal cyst are similar in other conditions,the following lesions should be included in the differ-ential diagnosis: a small OKC, mental foramen, smallneurofibroma or a radicular cyst at the foramen of alateral (accessory) pulp canal. The multiple (botryoid)cysts with a multilocular appearance may resemble asmall ameloblastoma. Clinical Features

Calcifying odontogenic cysts have a wide age distribu-tion that peaks at 10 to 19 years of age, with a mean ageof 36 years. A second incidence peak occurs during theseventh decade. Clinically, the lesion usually appears asa slow-growing, painless swelling of the jaw. Occasion-ally the patient complains of pain. In some cases theexpanding lesion may destroy the cortical plate, and thecystic mass may become palpable as it extends into thesoft tissue. The patient may report a discharge fromsuch advanced lesions. Aspiration often yields a viscous,granular, yellow fluid.

ManagementLateral periodontal cysts usually do not require sophis-ticated imaging because of their small size. Excisionalbiopsy or simple enucleation is the treatment of choice,since these cysts do not tend to recur.

CALCIFYING ODONTOGENIC CYST

SynonymsCalcifying epithelial odontogenic cyst or Gorlin cyst


400 PART V RAplOGRAPHIC INTERPRETATION OF PATHOLOGY

fibroodontoma, and calcifying epithelial odontogenictumor. The common position for the calcifying odon-togenic cyst is not common for either the fibroodon-toma or the calcifying epithelial odontogenic tumor.Finally, long-standing cysts may have dystrophic calcifi-cation, giving a similar appearance.

Radiographic FeaturesLocation. At least 75% of calcifying odontogenic cystsoccur in bone, with a nearly equal distribution betweenthe jaws. Most (75%) occur anterior to the first molar,especially associated with cuspids and incisors, wherethe cyst sometimes manifests as a pericoronal radiolu-cency.

ManagementAlthough this cyst does have some neoplastic charac-teristics, such as a tendency for continued growth, thetreatment should be enucleation and curettage.Because clinicians generally have little experience withthe more solid neoplastic variants, it is wise to followtreatment with periodic radiographic evaluation forrecurrence.

Periphery and shape. The periphery can vary from welldefined and corticated with a curved, cystlike shape-toill definec! and irregular.

Internal structure. The internal aspect can vary inappearance. It may be completely radiolucent; it mayshow evidence of small foci of calcified material thatappear as white flecks or small smooth pebbles; or itmay show even larger, solid, amorphous masses {Fig. 20-18). In rare cases the lesion may appear multilocular.

Effects on surrounding structures. Occasionally (20%to 50% of cases) the cyst is associated with a tooth (mostcommonly a cuspid) and impedes its eruption. Dis-placement of teeth and resorption of roots may occur.Perforation of the cortical plate may be seen radi-ographically with enlarging lesions.

DefinitionThe nasopalatine canal usually contains remnants ofthe nasopalatine duct, a primitive organ of smell, as wellas the nasopalatine vessels and nerves. Occasionally acyst forms in the nasopalatine canal when these em-bryonic epithelial remnants of the nasopalatine ductundergo proliferation and cystic degeneration.

Differential DiagnosisWhen no internal calcifications are evident and thislesion has a pericoronal position, it may be indistin-guishable from a dentigerous cyst. Other lesions thathave internal calcifications to be considered includean adenomatoid odontogenic tumor, ameloblastic

A BFIG. 20-18 A and 8, Calcifying odontogenic cyst related to the lateral incisor. Note thewell-defined, corticated border, internal calcifications, and resorption of part of the root ofthe central incisor.

NASOPALATINE DUCT CYST

SynonymsNasopalatine canal cyst, incisive canal cyst, nasopalatinecyst, median palatine cyst, or median anterior maxillary

cyst



Clinical FeaturesNasopalatine duct cysts acco~nt for about 10% of jawcysts. The age distribution is broad, with most casesbeing discovered in the fourth through sixth decades.The incidence is three times higher in males. Most ofthese cysts are asymptomatic or cause such mInorsymptoms that they are tolerated for long periods. Themost frequent complaint is a small, well-defined swel-ling just posterior to the palatine papilla. This swellingusually is fluctuant and blue if the cyst is near thesurface. The de~per nasopalatine duct cyst is coveredby normal-appearing mucosa unless it is ulcerated frommasticatory trauma. If the cyst expands, it may pene-trate the labial plate and produce a swelling below themaxillary labial frenum or to one side. The lesion alsomay bulge into the nasal cavity and distort the nasalseptum. Pressure from the cyst on the adjacentnasopalatine nerves that occupy the same canal maycause a burning sensation or numbness over the palatalmucosa. In some cases cystic fluid may drain into theoral cavity through a sinus tract or a remnant of thenasopalatine duct. The patient usually detects the fluidand reports a salty taste.

Differential DiagnosisThe most common differential diagnosis is a largeincisive foramen. A foramen larger than 6 mm maysimulate the appearance of a cyst. However, a clinicalexamination should revea,l the expansion characteristicof a cyst and other changes that occur with a space-occupying lesion, such as displacement of teeth. Alateral view of the anterior maxilla, using an occlusalfilm held outside the mouth and against the cheek, alsocan help in making the differential diagnosis, as can across-sectional (standard) occlusal view. If doubt stillexists, comparison with previous images may be useful,or aspiration may be attempted, or another image maybe made in 6 months to 1 year to assess any change insize. A radicular cyst or granuloma associated with acentral incisor is similar in appearance to an asymmet-ric nasopalatine cyst. The presence or absence of thelamina dura and enlargement of the periodontal liga-ment space around the apex of the central incisor indi-cate an inflammatory lesion. A vitality test of the centralincisor may be useful. A second periapical view taken ata different horizontal angulation should show analtered position of the image of a nasopalatine ductcyst, whereas a radicular cyst should remain centeredabout the apex of the central incisor.Radiographic Features

Location. Most nasopalatine duct cysts are found inthe nasopalatine foramen or canal. However, if thiscyst extends posteriorly to involve the hard palate(Fig. 20-19), it often is referred to as a medianpalatal cyst. If it expands anteriorly between thecentral incisors, destroying or expanding the labialplate of bone and causing the teeth to diverge, itsometimes is referred to as a median anterior max-illary cyst. This cyst may not always be positioned

symmetrically.

ManagementThe appropriate treatment for a nasopalatine cyst isenucleation, preferably from the palate to avoid thenasopalatine nerve. If the cyst is large and the dangerexists of devitalizing the tooth or creating a naso-oralor antro-oral fistula, the surgeon may elect to marsupi-alize the cyst.

Periphery and shape. The periphery usually iswell defined and corticated and is circular or ovalin shape. The shadow of the nasal spine some-times is superimposed on the cyst, giving it a heartshape.

NASOLABIAL CYST

SynonymNasoalveolar cyst

Definition

The exact origin of nasolabial cysts is unknown. They

may be fissural cysts arising from the epithelial rests in

fusion lines of the globular, lateral nasal, and maxillary

processes. Alternatively, the source of the epithelium

may be from the embryonic nasolacrimal duct, which

initially lies on the bone surface.

Internal structure. Most nasopalatine duct cysts aretotally radiolucent. Some rare cysts may have internaldystrophic calcifications, which may appear as ill-defined, amorphous, scattered radiopacities..

Effects on surrounding structures. Most commonly thiscyst causes the roots of the central incisors to diverge,and occasionally root resorption occurs (Fig. 20-20).Seen from a lateral perspective, the cyst may expand thelabial cortex as well as the palatal cortex (Fig. 20-21).The floor of the nasal fossa may be displaced in a supe-rior direction.

Clinical FeaturesWhen this rare lesion is small, it may produce a verysubtle, unilateral swelling of the nasolabial fold and mayelicit pain or discomfort. When large, it may bulge intothe floor of the nasal cavity, causing some obstruction,flaring of the alae, distortion of the nostrils, and full-ness of the upper lip. If infected, it may drain into the


RADIOGRAPHIC INTERPRETATION OF PATHOLOGY402 PART V

-

c

~

D I

FIG. 20-19 Nasopalatine duct cysts. Note the uniform periodontal membrane spacearound all the apices. A through D show variations in size. The differential diagnosis of asmaller cyst with a normal nasopalatine foramen may be difficult.


,403CHAPTER 20 CYSTS OF THE JAWS

nasal cavity. It usually is unilateral, but bilateral lesionshave occurred. The age of detection ranges from 12 to75 years, with a mean age 01 44 years. About 75% ofthese lesions occur in females.

lesion, plain radiographs may not show any detec-table changes. The investigation could include eithercomputed tomography (CT) or magnetic resonanceimaging (MRI), both of which can provide an image ofsoft tissues (Fig. 20-22).

Radiographic FeaturesLocation. Nasolabial cysts are primarily soft tissuelesions located adjacent to the alveolar process abovethe apices of the incisors. Because this is a soft tissue

Periphery and shape. Thin axial CT images using thesoft tissue algorithm with contrast reveal a circular oroval lesion with slight soft tissue enhancement of the

periphery.

Internal structure. In CT images using the soft tissuealgorithm the internal aspect appears homogeneousand relatively radiolucent compared with the sur-rounding soft tissues.

Effects on surrounding structures. Occasionally a cystcauses erosion of the underlying bone (Fig. 20-23), pro-ducing an increased radiolucency of the alveolarprocess beneath the cyst and apical to the incisors. Also,the usual outline of the inferior border of the nasalfossa may become distorted, resulting in a posteriorbowing of this margin.

Differential DiagnosisThe swelling caused by an infected nasolabial cyst maysimulate an acute dentoalveolar abscess. It is importantto establish the vitality of the adjacent teeth. This cystmay also resemble a nasal furuncle if it pushes upwardinto the floor of the nasal cavity. A large mucousextravasation ~yst or a cystic salivary adenoma should

FIG. 20-20 A nasopalatine canal cyst causing externalroot resorption of a maxillary central incisor.

A BFIG. 20-21 A nasopalatine canal cyst viewed from two perspectives: (A) a standardocclusal view and (B) from the lateral aspect, which is created by placing the film outsidethe mouth against the cheek and directing the x-ray beam at a tangent to the labial surfaceof the central incisors.


RADIOGRAPHIC INTERPRETATION OF PATHOLOG'404 PART V

mis and cutaneous appendages and filled with keratinor sebaceous material (and in rare cases with bone,teeth, muscle, or hair, in which case they are properlycalled teratomas).

Clinical FeaturesDermoid cysts may develop in the soft tissues at any timefrom birth, but they usually become clinically apparentbetween 12 and 25 years of age, about equally distrib-uted between the sexes. The swelling, which is slow andpainless, can grow to several centimeters in diameter,and when located in the neck or tongue, it may inter-fere with breathing, speaking, and eating. Dependingon how deep the cyst is positioned in the neck, it candeform the submental area. On palpation these cystsmay be fluctuant or doughy, according to their con-tents. Because they usually are in the midline, they donot affect the teeth.

FIG. 20-22 Nasolabial cyst shown in an axial CT imageusing a soft tissue algorithm. Note the well-defined periph-ery and the erosion of the labial aspect of the alveolar process

(arrow).Radiographic FeaturesBecause dermoid cysts are soft tissue cysts, diagnosticimaging is best accomplished by CT or MR!.

Location. A dermoid cyst is a rare developmentalanomaly that may occur anywhere in the body. About10% or fewer arise in the head and neck, and only 1 %to 2% develop in the oral cavity. Of these, about 25%occur in the floor of the mouth and on the tongue.They may be midline or lateral in location.

Periphery and ,s-hape. The periphery of the lesionusually is well defined by more radiopaque soft tissue ofthis cyst compared with surrounding soft tissue, as seenin CT scans.

Internal structure. Dermoid cysts seldom have anyinternal mineralized structures when they occur in theoral cavity; therefore they are radiolucent on conven-tional radiographs. However, a CT scan of the area mayreveal a soft tissue multilocular appearance (Fig. 20-24).If teeth or bone form in the cyst, their radiopaqueimages, with characteristic shapes and densities, areapparent on the radiograph.

FIG. 20-23 Occlusal view ofa nasolabial cyst. The radi-ograph shows erosion of the alveolar bone (0) and elevationof the floor of the nasal fossa (arrows). (From MontenegroChineallato LE, Demante JH: Oral Surg 58:729, 1984.)

also be considered in the differential diagnosis of anuninfected nasolabial cyst.

Differential DiagnosisLesions that are clinically similar to dermoid cysts areranula (unilateral or bilateral blockage of Wharton'sducts), thyroglossal duct cysts, cystic hygromas,branchial cleft cysts, cellulitis, tumors (lipoma andliposarcoma), and normal fat masses in the submentalarea.

ManagementThe nasolabial cyst should be excised through an intra-oral approach. These cysts do not tend to recur.

DERMOID CYST

DefinitionDermoid cysts are a cystic form of a teratoma thoughtto be derived from trapped embryonic cells that aretotipotential. The resulting cysts are lined with epider-

ManagementDermoid cysts do not recur afte,r surgical removal,



DefinitionA simple bone cyst (SBC) is a cavity within bone that islined with connective tissue. It may be empty, or it maycontain fluid. However, because it has no epitheliallining, it is not a true cyst. The etiology of SBCs isunknown, although they may be a localized aberrationin normal bone remodeling or metabolism. This theoryis supported indirectly by the fact that these bony cavi-ties often occur inside lesions of cemento-osseous dys--plasia

and fibrous dysplasia. No evidence exists tosupport a traumatic cause.

Clinical FeaturesSBCs are very common lesions. Most occur in the first2 decades of life, with a mean age of 17 years. Thelesion shows a male predominance of approximately2: 1. Multiple SBCs can develop, especially when thedisorder occurs with cemento-osseous dysplasia. Theoccurrence of SBCs in cemento-osseous dysplasia isseen in an older population, with a mean age of 42years, and with a female predominance of 4: 1. SBCsare asymptomatic in most cases, but occasionally painor tenderness may be present, especially if the cysthas become secondarily infected. Expansion of themandible or tooth movement is possible but unusual.The teeth in the affected region usually are vital. MostSBCs are discoyered only by chance, during radi-ographic examin~ons, and for this reason they canbecome quite large. There is no significant incidenceof pathologic fractures. When aspiration is productive,usually only a few milliliters of straw- colored or serosan-guineous fluid are obtained.

FIG. 20-24 CT scan of a dermoid cyst showing an encap-sulated mass on the left and several soft tissue loculations.(From Hunter T8 et al: Am J Roentgenol141 :1229, 1983.)

FORMER CYSTS

In recent years it has become clear that some namesused to describe diStinct entities are no longer valid.These names include primordial cysts (now recognizedlargely to be odontogenic keratocysts [OKCs]), medianpalatal cysts (now recognized as a variant of thenasopalatine duct cyst), and median mandibular and glob-ulomaxillary cysts (because the entrapment of epithe-lium theory is no longer accepted). Globulomaxillarycysts are now recognized to be radicular or lateral peri-odontal cysts or OKCs.

Radiographic FeaturesLocation. Almost all SBCs are found in the mandible(Fig. 20-25); in rare cases they develop in the maxilla.The lesion can occur anywhere in the mandible but isseen most often in the ramus and posterior mandiblein -older patients. SBCs also frequently occur withcemento-osseous and fibrous dysplasia.

Cystlike LesionsPeriphery and shape. The margin may vary from a well-defined, delicate cortex to an ill-defined border thatblends into the surrounding bone. The boundaryusually is better defined in the alveolar process aroundthe teeth than in the inferior aspect of the body of themandible. The shape most often is smooth and curved,like a cyst, with an oval or scalloped border. The lesionoften scallops between the roots of the teeth (see Fig.20-25).

SIMPLE BONE CYST

SynonymsTraumatic bone cyst, hemorrhagic bone cyst, extrava-sation cyst, progressive bone cavity, solitary bone cyst,or unicameral bone cyst

Internal structure. The internal structure is totallyradiolucent, but occasionally it may appear multilocu-lar, although the lesion does not contain true septa.

Simple bone cysts are included in this chapter becauseof their historic classification and because the charac-teristics and behavior seen in diagnostic imaging arecystic in nature. However, it is important to rememberthat these lesions are not true cysts.



A B CFIG. 20-25 Panoramic film demonstrating a simple bone cyst (A), an occlusal film (8),and a periapical film (C). The occlusal film shows that no expansion has occurred in thebuccal or lingual cortical plates. Note that, except for the superior border, the borders areill-defined and that the lesion has scalloped around the teeth and thinned the inferiorborder of the mandible but the lamina dura is still present.

B CFIG. 20-26 An SBC has a multilocular appearance in this lateral oblique view of themandible (A). The periapical view (B) appears to show internal septa (arrows) because ofthe scalloping of the endosteal surface of the cortical plates, as is seen in the inferior cortex(arrows) in A and of the endosteal surface of the buccal cortex in the occlusal view (C).

A

This appearance is the result of pronounced scallopingof the endosteal surface of either the buccal or lingualplates (Fig. 20-26). The ridges of bone produced by thescalloping give the appearance of septa on a lateral viewof the mandible.

Effects on surrounding structures. In most cases theselesions have no effect on the surrounding teeth,although rare cases of tooth displacement and resorp-tion have been documented. Often the lesion involvesall the bone around the roots of the teeth but leaves thelamina dura intact or only partly disrupted (Fig. 20-27).Similarly, the sparing of the cortical boundary of thecrypt around a developing tooth is characteristic. Aspreviously mentioned, these lesions have a propensityto scallop the endosteal surface of the outer cortex of

FIG. 20-27 An SBC in which the lamina dura is main-tained on most root surfaces involved with the lesion, exceptfor the mesial surface of the distal root tip of the first molar.


-,


FIG. 20-28 A and B, An SBC extending from the first bicuspid posteriorly to the baseof the ramus and occupying most of the mandible. Considering the extent of the lesion,very little expansion of the buccal or lingual cortical plates has occurred, as can be seenin the axial CT image (B) using bone algorithm.

the mandible. SBCs also have a tendency to grow alongthe long axis of the bone, causing minimal expansion(Fig. 20-28). However, expansion of the involved bonecan occur and is more common with larger lesions (Fig.20-29).

Differential DiagnosisAn SBC may have an appearance similar to that of atrue cyst, especially an odontogenic keratocyst (OKC).This is because OKCs tend to grow along bone with verylittle expansion and often have scalloped borderssimilar to those of an SBC. However, OKCs usuallyhave a more definite cortical boundary, resorb and dis-place teeth, and occur in an older age group. Becausethe SBC may remove bone around teeth withoutaffecting the teeth, there may be a tendency to includea malignant lesion in the differential. However,maintenance of some lamina dura and the lack ofan invasive periphery and bone destruction should beenough to remove this category of diseases fromconsideration.

.,

The diagnosis relif;!;S primarily on radiographic andsurgical observations because the histopathologicaspects are not characteristic. These lesions occasion-ally heal spontaneously. A biopsy and analysis of ahealing cyst may falsely indicate the presence of anossifying fibroma or fibrous dysplasia because of theformation of new immature bone (Fig. 20-30). FIG. 20-29 An SBC (arrow) positioned in the anterior of

the mandible. Note that the superior aspect of the periph-eral cortex is better defined than the inferior border and thatevidence exists of some expansion of the mandible's lingualcortex, which in part may due to muscle attachment at thegenial tubercles.

ManagementThe customary treatment isthe lesion and careful cuusually fuitiates bleeding

a conservative opening intorettage of the lining; this

and subsequent healing.



Lustmann ], Bodner L: Dentigerous cysts associated withsupernumerary teeth, Int] Oral Maxillofac Surg 17 (2): 1 00,1988.

Main DMG: Follicular cysts of mandibular third molar teeth:radiological evaluation of enlargement, DentomaxillofacRadioI18:156, 1989.

Maxymiw WG, Wood RE: Carcinoma arising in a dentigerouscyst: a case report and review of the literature,] Oral Max-illofac Surg 49(6):639, 1991.

FIG. 20-30 An axial CT image using a bone algorithmdisplaying a small SBC in the process of healing (arrow). Notethe fine internal granular bone and very slight expansion ofthe ramus.

Buccal bifurcation cystBohay RN, Weinberg S: The paradental cyst of the mandibu-

lar permanent first molar: report of a bilateral case, J DentChild Sept-Oct:361, 1992.

Fowler CB, Brannon RB: The paradental cyst: a clinicopatho-logic study of six new cases and review of the literature,J Oral Maxillofac Surg 47:243, 1989.

Packota GV et al: Paradental cysts on mandiqular first molarsin children: report of five cases, Dentomaxillo(ac Radiol19:126, 1990.

Shear M: Cysts of the oral regions, Bristol, UK, 1976, JohnWright & Sons.

Stoneman DW, Worth HM: The mandibular infected buccalcyst-molar area, Dent Radiogr Photogr 56:1','983.Spontaneous healing has been reported. Periodic

follow-up radiographic examinations are advisable,especially if the patient declines treatment. Theselesions can recur, but it is rare.

BI BLIOG RAPH Y

Shear M: Cysts of the jaws: recent advances, ] Oral Pathol14:43, 1985. .

Shear M: Developmental odontogenic cysts: an update,] OralPathol Med 23:1, 1994.

Odontogenic keratocystBrannon RB: The odontogenic keratocyst: a clinicopatholog-

ical study of 312 cases. I. Clinical features, Oral Surg 42:54,1976.

Browne RM: The odqntokeratocyst: clinical aspects, Br DentJ 128:225, 1970.

Frame JW, Wake MJC: Computerized axial tomography in theassessment of mandibular keratocy~ts, Br Dent J 153:93,1982.

Kakarantza-Angelopoulou E, Nicolatou 0: Odontogenickeratocysts: clinicopathologic study of 87 cases, J OralMaxillofac Surg 48(6):593, 1990.

Kondell PA, Wiberg J: Odontogenic keratocysts: afollow-up study of 29 cases, Swed Dent J 12(1-2):57,1988.

Partridge M, TowersJF: The primordial cyst (odontogenickeratocyst): its tumor-like characteristics and behavior, Br JOral Maxillofac Surg 25:271, 1987.

Shear M: The aggressive nature of the odontogenic kerato-cyst: is it a benign cystic neoplasm?: Part 1, Oral Oncol38:219,2002.

ODONTOGENIC CYSTS

Radicular cystStockdale CR, Chandler NP: The nature of the periapical

lesion: a review of 1108 cases,] Dent 16(3):123,1988.SyIjauanen S et al: Radiological interpretation of the periapi-

cal cysts and granulomas, Dentomaxillofac Radiol 11:89,1982.

Toller PA: Origin and growth of cysts of the jaws, Ann R ColISurg Engl 40:306, 1967.

Wood RE et al: Radicular cysts of primary teeth mimickingpremolar dentigerous cysts: report of three cases, ASDC]Dent Child 55(4):288,1988.

Residual cystHigh AS, Hirschmann PN: Age changes in residual cysts,

J Oral PathoI15:524, 1986.Schwimmer AM et al: Squamous cell carcinoma arising in

residual odontogenic cyst: report of a case and review of lit-erature, Oral Surg 72(2) :218, 1991.

Dentigerous cystDaley TD, Wysocki GP: The small dentigerous cyst, Oral Surg

Oral Med Oral Pathol Oral Radiol Endod 79:77,1995.

Basal cell nevus syndrome

Angelopoulou E, Angelopoulos AP: Lateral periodontal cyst:review of the literature and report of a case, J Periodontol61(2):126,1990.

Donatsky 0 et al: Clinical, radiographic, and histologic fea-tures of the basal cell nevus syndrome, IntJ Oral Surg 5:19,1976.

Evans DC et al: The incidence of Corlin syndrome in 173 con-secutive cases of medulloblastoma, Br J Cancer 64(5):959,1991.

Gorlin RJ: Nevoid basal cell carcinoma syndrome, Medicine66(2):98, 1987.



Hartziotis]: Median palatine cyst: report of a case,] Oral Surg24:343, 1966.

Nortje C], Farman AG: Nasopalatine duct cyst: an aggressivecondition in adolescent Negroes from South Africa? Int]Oral Surg 7:65, 1978.

lateral periodonta'l cystRegeziJA et al: The pathology of head and neck tumors: cysts

of the jaw. XII, Head Neck Surg 4:48,1981.Shear M, Pindborg.D: Microscopic features of the lateral peri-

odontal cyst, ScandJ Dent Res 83:103, 1975.Weathers DR, Waldron CA: Unusual multilocular cysts of the

jaws (botryoid odontogenic cysts), J Periodontol 41:~49,1970.

Wysocki GP et al: Histogenesis of the lateral periodontal cystand the gingival cyst of the adult, Oral Surg 50:327, 1980.

Nasolabial cystRoed-Petersen B: Nasolabial cysts, Br ] Oral Surg 7:85,

1970.Seward GR: Nasolabial cysts and their radiology, Dent Pract

12:154, 1962.Walsh-Waring GP: Nasoalveolar cysts: aetiology, presentation,

and treatment,] Laryngol OtoI81:263, 1967.Calcifying odontC?genic cystAltini M, Farman AG: The calcifying odontogenic cyst: eight

new cases and a review of the literature, Oral Surg 20:751,

1975.Fejerskov 0, KroughJ: The calcifying ghost cell odontogenic

tumor or the calcifying odontogenic cyst, J Oral Pathol

1:272, 1972.Freedman PD et al: Calcifying odontogenic cyst, Oral Surg

40:93, 1975.Hirshberg A et al: Calcifying odontogenic cyst associated with

odontoma,J Oral Maxillofac Surg 52:555,1994.Saito I et al: Calcifying odontogenic cyst: case reports, varia-

tions, and tumorous potential, J Nihon Univ Sch Dent

24:69, 1982.

NONODONTOGENIC CYSTS

Nasopalatine duct cystAbrams AM et al: Nasopalatine cysts, Oral Surg 16:306, 1963.Allard RHB et al: Nasopalatine duct cyst, Int ] Oral Surg

10:447,1981.

Dermoid cystSeward GR: Dermoid cysts of the floor of the mouth, Br J Oral

Surg 3:36, 1965.

CYSTLIKE LESIONS

Simple bone cystFeinberg S et al: Recurrent "traumatic" bone cysts of the

mandible, Oral Surg 57:418, 1984.Kaugars GE, Cale AE: Traumatic bone cyst, Oral Surg Oral

Med Oral Pathol 63:318, 1987.Saito Yet al: Simple bone cyst: a clinical and histopathologic

study of fifteen cases, Oral Surg Oral Med Oral Pathol74:487,1992.

Sapp PJ, Stark ML: Self-healing traumatic bone cysts, OralSurg Oral Med Oral Pathol 69:597,1990.

JH Damante JH et al: Spontaneous resolution of simple bonecysts, Dentomaxillofac Radiol 31:182, 2002.


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