Lecture 15

Developmental cyst

Developmental cysts

Some of these have been considered historically as "fissural"

cysts because they were thought to arise from epithelium

entrapped along embryonal lines of fusion.

• Regardless of their origin, once cysts develop in the oral and

maxillofacial region, they tend to slowly increase in size,

possibly in response to a slightly elevated hydrostatic luminal

pressure.

Nasopalatine duct cyst: an intaosseous developmental cyst of

the midline of the anterior palate, derived from the island of

epithelium remaining after closure of the embryonic nasopalatine

duct.

• The nasopalatine duct cyst, also termed incisive canal cyst, arises from

embryonic remnants of the nasopalatine duct.

• Most of these cysts develop in the midline of the anterior maxilla near

the incisive foramen.

Radiographical features:

• The nasopalatine duct cyst present as a well-

circumscribed oval or heart-shaped radiolucency

located in the midline of the anterior maxilla

between the roots of the central incisors.

Histopathology• These cyst are lined by a layer of ciliated columnar (respiratory), cuboidal , or

stratified squamous epithelium or by a mixture of these epithelial types.

• If inflammation is present, it usually consists of an infiltrate of plasma cells and

lymphocyte.

• The cyst capsule typically exhibits the prominent component of blood vessels and

peripheral nerves that comprise normal incisive canal contents. The presence of these

neurovascular elements can be helpful in reaching a microscopic diagnosis.

• In addition, occasional small lobules of salivary type mucus glands may be seen in

the cyst wall .premalignant or malignant transformation of the epithelial lining in this

cyst has not been reported.

• The histologic features of the cyst of the incisive papilla closely resemble those of the

nasopalatine duct cyst.

Treatment:

Treatment of the nasopalatine duct cyst is by surgical

enucleation , using a palatal approach. Recurrence of

this cyst is rare.

Nasolabial cyst:• A developmental cyst of the soft tissue

of the anterior mucobuccal fold beneath

the ala of the nose.

• most likely derived from remnants of the

inferior portion of the nasolacrimal duct.

• Also known as the naso-alveolar cyst

and the klestadt cyst.

• this rare condition occurs entirely in the

soft tissues of the anterior maxillary

vestibule, below the ala of the nose and

deep in the nasolabial crease (fold).

Clinical features• This cyst is a unilateral or occasionally bilateral painless soft tissue swelling.

• If the upper lip is retracted, this cyst also can be seen inta-orally as a swelling

located at the depth of the maxillary vestibule.

• Most of these cysts occur in the fourth and fifth decades of life and have a

female predilection of approximately 3 to 1.

• Because this cyst is located entirely within soft tissue, it is not

readily apparent radiographically unless contrast medium is

injected into the cystic lumen to facilitate visualization.

• Focal pressure-induced bone resorption of the anterior maxilla

can be occasionally demonstrated on radiographs and is most

readily seen in the edentulous patients.

Histology:

• the cyst is lined by a layer of pseudo

stratified columnar epithelium exhibiting

variable numbers of mucus (goblet) cells or

by a ductal type of cuboidal epithelium.

• A lining of stratified squamous epithelium

can be seen in some lesion.

• Some degree of folding of the cyst lining

and of the associated connective tissue is

often seen.

• A narrow zone of dense, homogeneous,

fibrous tissue is usually seen adjacent to the

epithelial lining.

• Inflammation is generally absent.

Treatment:

A nasolabial cyst is treated by surgical enucleation

with particular care being exercised to prevent the

lesion's perforation and collapse. Recurrence is rare.

Lymphoepithelial cysts:

• A cyst with a lumen lined by a keratinized stratified squamous

epithelium and a capsule containing multiple normal lymphoid follicles

and a dense accumulation of normal lymphocytes.

• Lymphoepithelial cysts are relatively uncommon lesion that occurs in

several areas of the head and neck, most commonly in the floor of the

mouth and on the lateral aspect of the neck.

• Those occurring intraorally are termed oral lymphoepithelial cysts, and

those occurring on the lateral aspect of the neck are termed cervical

lymphoepithelial cysts. Although cysts in the oral cavity are

considerable smaller than those on the lateral aspect of the neck, their

histopathologic features are essentially the same.

Oral lymphoepithelial cyst • A lymphoepithelial cyst commonly located intraorally on the posterior

lateral tongue and the anterior floor of the mouth.

• The Oral lymphoepithelial cyst , also termed benign lymphoepithelial

cyst, most commonly develops where extratonsillar lymphoid tissue (oral

tonsil) is found.

• The most common sites are the anterior floor of the mouth and the

posterior lateral border of the tongue.

• It appears to develop from epithelial invaginations (crypts) that become

detached from the surface mucosa and entrapped within the lymphoid

tissue; cyst formation ensues.

Clinical features

• The oral lymphoepithelial cyst is most commonly found on the

anterior floor of the mouth and on the posterior lateral borders

of the tongue. However, it can also occur on the ventral surface

of the tongue, soft palate, tonsillar pillars, and oropharynx.

• It is a symptomatic, yellow or tan, superficial submucosal mass

that usually measures less than 1 cm in diameter .

Histopathology

• The cyst is lined by a relatively thin layer of parakeratinized squamous

epithelium surrounded by a well-defined mass of normal lymphoid tissue

exhibiting variable numbers of germinal centers.

• The cystic lumen is usually filled with desquamated parakeratin.

Occasionally, the pore or crypt that communicates between the surface

mucosa and the cystic lumen can be seen microscopically. The presence of

bacteria within the cystic lumen in some of these cysts is also evidence that

communication with the oral cavity is present.

Cervical lymphoepithelial cyst:

• The cervical lymphoepithelial cyst, also commonly termed

branchial cleft cyst or benign cystic lymph node, occurs on the

lateral aspect of the neck, usually anterior to the

sternocleidomastoid muscle.

• It is thought to be derived from epithelium entrapped within

lymphoid tissues of the neck during embryologic

development.

Clinical features• The cyst becomes apparent in late childhood or early

adulthood as a painless swelling on the lateral aspect of

the neck anterior to the sternomastoid muscle.

• A draining fistula that communicates between the cyst

and the overlying skin surface occasionally develops.

Histopathology

The cyst lumen is usually lined by a thin layer of

stratified squamous epithelium and contain

desquamated orthokeratin , the capsule wall is

thickened , consisting of a fibrous connective tissue

containing large numbers of well-formed lymphoid

follicles.

CERVICALLYMPHOEPITHELIAL CYST.MEDIUM-POWERED VIEW SHOWING A CYST LINED BY STRATIFIED

SQUAMOUS EPITHELIUM. NOTE THE LYMPHOID TISSUE IN THE CYST WALL.

Treatment:

As with its intraoral counterpart, the cervical

lymphoepithelial cyst is treated by conservative

surgical excision; recurrence is rare.

Thyroglossal tract cyst: • A cyst located above the thyroid gland and beneath the base of the tongue,

with a lumen lined by a mixture of epithelial cell types derived from

remnants of the embryonic thyroglossal tract and often containing thyroid

tissue in the capsule.

• The thyroglossal tract cyst is a relatively uncommon lesion derived from

embryologic remnant of the thyroglossal tract. This tract extends from the

foramen caecum on the middorsum of the tongue to the thyroid gland.

Clinical features:

• This cyst occurs primarily in children and young adults.

• presents as an asymptomatic, slowly enlarging, and mobile

swelling involving the midline of the anterior neck above the

thyroid gland.

• A small percentage of these cysts occur within the tongue,

where they can cause dysphagia.

THYROGLOSSAL DUCT CYST. SWELLING (ARROW) OF THE ANTERIOR MIDLINE OF THE NECK.

Histopathology:

• This cyst is lined by stratified squamous epithelium, ciliated

columnar epithelium, transitional epithelium, or a mixture of

epithelium types.

• The cyst capsule can exhibit a number of additional findings

including lymphoid aggregates, thyroid tissue mucus glands,

and sebaceous glands.

• Carcinoma can occasionally develop from the lining of

thyroglossal tract cysts and from remnants of the thyroglossal

tract.

THYROGLOSSAL DUET CYST . CYST (TOP) LINED BY STRATIFIED SQUAMOUS EPITHELIUM. THYROID FOLLICLES CAN BE SEEN INTHE CYST WALL (BOTTOM).

Treatment:

The treatment of the thyroglossal tract cyst requires

complete surgical excision, because recurrence is a distinct

possibility. In an effort to minimize recurrence of cysts

involving the hyoid area, it is recommended that the central

portion of the hyoid bone and its associated remnants of

thyroglossal tract be removed.

Dermoid cyst: • a cyst of the midline of the upper neck or the anterior floor of

the mouth of young patients, derived from remnants of

embryonic skin, consisting of a lumen lined by a keratinized

stratified squamous epithelium, and containing one or more

skin appendages such as hair, sweat, or sebaceous glands.

• Most of these cysts occur in the head and neck region ,

primarily in the skin around the eye and the anterior upper

neck, extending superiorly into the floor of the mouth.

DERMOID CYST. FLUCTUANT MIDLINE SWELLING IN THEFLOOR OF THE MOUTH.

Clinical features:• The dermoid cyst is a lesion of young adults (teenagers).

• no gender predilection is seen.

• Cysts of the anterior upper neck or floor of the mouth present as painless

swellings.

• Cysts that develop above the mylohyoid muscle present as a midline

swelling in the sublingual (floor of the mouth) area. In this location the cyst

results in elevation of the tongue and can interfere with eating and

speaking.

• Cysts that develop below the mylohyoid muscle appear as a midline

swelling in the submandibular and submental region.

• The size of these cysts is variable, but most are 2 cm or less in diameter.

Histopathology:

• A layer of orthokeratinized squamous epithelium exhibiting

variable number of dermal appendages, including hair

follicle , sebaceous glands, and associated erector pili

muscles lines the cyst.

• The cystic lumen is generally filled with a mixture of

desquamated keratin, sebum, and hair shafts. The cyst

capsule is composed of generally free of inflammation.

DERMOID CYST. SQUAMOUS EPITHELIA L LINING (TOP).WITH HAIR FOLLICLE (F) AND SEBACEOUSGLANDS (S) IN THE CYST WALL.

Treatment:

This cyst is best treated by surgical enucleation or excision.

Recurrence is uncommon.

Epidermoid cyst:• A cyst of skin with a lumen lined by keratinizing stratified squamous

epithelium, usually filled with keratin and without skin appendages in the

capsule wall.

• The epidermoid cyst closely resembles a dermoid cyst, except that the

former exhibit no dermal appendages.

• They are lined by orthokeratinized squamous epithelium and exhibit a

lumen that is generally filled with desquamated keratin. The cyst wall

consists of a narrow zone of compressed fibrous connective tissue that is

generally free of inflammation.

• This cyst is treated by surgical enucleation or excision.

• Recurrence is uncommon.

EPIDERMOID CYST . FLUCTUANT NODULE AT THE LATERALEDGE OF TH EEYEBROW.

EPIDERMOID CYST. INFANT.

EPIDERMOID CYST. A. L OW-POWER VIEW SHOWING A KERATIN-FILLED CYSTIC CAVITY. B, HIGHPOWERED VIEW SHOWING STRAT IFIED SQUAMOUS EPITHELIAL LINING WITH ORTHOKERATIN PRODUCTION.

Heterotopic oral Gastrointestinal cyst:• The heterotopic oral gastrointestinal cyst is a rare and unusual developmental

entity .

• most commonly found in the tongue or the floor of the mouth of infants or

young children.

• The theory of undifferentiated endodermal entrapment during the fourth or fifth

week of embryonic development, followed by gastrointestinal differentiation.

• This cyst is treated by surgical excision; recurrence is uncommon.

"GLOBULOMAXILLARY CYST":

• fissural cyst that arise from epithelium entrapped during fusion of the globular

portion of the medial nasal process with the maxillary process.

• Current theory holds that most (if not all) cysts that develop in the

globulomaxillary area are actually of odontogenic origin.

 

Clinical and Radiographic Features

• The "globulomaxillary cyst" classically develops between the maxillary

lateral incisor and cuspid teeth.

• Although occasional globulomaxillary lesions have been reported 'between

the central a lateral Radiographs typically demonstrate a well-circumscribed

unilocular radiolucency between and apical to the teeth because this

radiolucency often is constricted as it extends down between the teeth. It

may resemble an inverted pear. As the lesion expands, tipping of the tooth

roots may occur.

 

Histopathologic Features: Virtually cysts in the globule-maxiliary

region can be explained on an odontogenic basis.

• Many are lined by inflamed stratified squamous epithelium and are

consistent with periapical cysts.

• some exhibit specific histopathologic features of an odontogenic keratocyst

or developmental lateral periodontal cyst. It also has been theorized that

some of these lesions may arise from inflammation of the reduced enamel

epithelium at the time of eruption of the teeth.

• On rare occasions cysts in the globulomaxiliary area may be lined by

pseudostratified ciliated columnar epithelium.

Treatment and Prognosis

• Treatment of cysts in the globulomaxillary area usually

consists of surgical enucleation. If the lesion can be related to

an adjacent non vital tooth, then endodontic therapy may be

appropriate. Prognosis depends on the specific histopathologic

type of cyst. Except for the odontogenic keratocyst, the

recurrence potential should below.

PALATALCYSTS OFTHE NEWBORN

(EPSTEIN'SPEARLS; BOHN'S NODULES)

• Small developmental cysts are a common finding on the palate of newborn

infants.

• It has been theorized that these "inclusion" cysts may arise in one of two

ways:

• First, as the palatal shelves meet and fuse in the midline during embryonic

life to form the secondary palate, small islands of epithelium may become

entrapped below the surface along the median palatal raphe and form cysts.

• Second, these cysts may arise from epithelial remnants derived tram the

development of the minor salivary glands of the palate.

EPSTEIN'S PEARL S. SMALL KERATIN -FILLED CYSTS AT THEJUNCTION OF THE HARD AND SOFT PALATES.

Clinical Features• Palatal cysts of the newborn are quite common and have

been reported in 65% to 85% of neonates.

• The cysts are small, 1 to 3 mm white or yellowish-white

papules that appear most often along the midline near the

junction of the hard and soft palates,

• Occasionally, they may occur in a more anterior location

along the raphe or on the posterior palate lateral to the

midline.

Histopathologic Features

• Microscopic examination reveals keratin-filled cysts that

are lined by stratified squamous epithelium; sometimes

these cysts demonstrate a communication with the mucosal

surface.

Treatment and Prognosis

Palatal cysts of the newborn are innocuous lesions, and no

treatment is required. They are self-healing and rarely

observable several weeks after birth. Presumably the

epithelium degenerates, or the cysts rupture onto the mucosal

surface and eliminate their keratin contents.

MEDIAN PALATAL (PALATINE) CYST:

The median palatal cyst is a rare fissural cyst that theoretically

develops from epithelium entrapped along the embryonic line of

fusion of the lateral palatal shelves of the maxilla. This cyst may be

difficult to distinguish from a nasopalatine duct cyst. In fact most

"median palatal cysts" may represent posteriorly positioned

nasopalatine duct cysts. Because the nasopalatine ducts course

posteriorly and superiorly as they extend from the incisive canal to

the nasal cavity, a nasopalatine duct cyst that arises from posterior

remnants of this duct near the nasal cavity might be mistaken for a

median palatal cyst.

MEDIAN PALATAL CYST. WELL-CIRCUMSCRIBED RADIOLUCENCYAPICAL TO THE MAXILLARY INCISORS IN THE MIDLINE. AT SURGERY THE LESION WAS UNRELATED TO THE INCISIVE CANAL.

On the other hand if a true median palatal cyst was to develop toward the anterior portion of the hard palate. It could easily be mistaken for a nasopalatine duct cyst.

Clinical and Radiographic Features• The median palatal cyst presents as a firm or fluctuant swelling of the midline of the

hard palate posterior to the palatine papilla.

• The lesion appears most frequently in young adults. Often it is asymptomatic. But

some patients complain of pain or expansion.

• The average size of this cyst is 2 X 2 cm, but sometimes it can become quite large.

• Occlusal radiographs demonstrate a well-circumscribed radiolucency in the midline

of the hard palate.

• Occasional reported cases have been associated with divergence of the central

incisors. Although it may be difficult to rule out a nasopalatine duct cyst in these

instances. It must be stressed that a true median palatal cyst should exhibit clinical

enlargement of the palate.

• A midline radiolucency without clinical evidence of expansion is probably a

nasopalatine duct cyst.

Histopathologic Features

• Microscopic examination shows a cyst that is usually lined by stratified

squamous epithelium. Areas of ciliated pseudostratified columnar

epithelium have been reported in some cases.

• Chronic inflammation may be present in the cyst wall.

Treatment and Prognosis

The median palatal cyst is treated by surgical removal.

Recurrence should not be expected.

“MEDIAN MANDIBULAR CYST”:

The “median mandibular cyst” is a controversial lesion of questionable existence.

Theoretically, it represents a fissural cyst in the anterior midline of the mandible that

develops from epithelium entrapped during fusion of the halves of the mandible during

embryonic life.

it appears likely that most (if not all) of these midline cysts are of odontogenic origin.

Many purported cases would be classified today as examples of the glandular

odontogenic cyst, which has a propensity for occurrence in the midline mandibular

region. Others could be classified as periapical cysts, odontogenic keratocysts, or lateral

periodontal cysts. Because a fissural cyst in this region probably does not exist, the term

median mandibular cyst should no longer be used.

Other Rare Developmental Anomalies:HEMIHYPERPLASIA (HEMIHYPERTROPHY):

Hemihyperplasia is a rare developmental anomaly characterized by asymmetric

overgrowth of one or more body parts. Although the condition is known more commonly

as hemihypertrophy, it actually represents a hyperplasia of the tissues rather than a

hypertrophy. Hemihyperplasia can be an isolated finding but it also may be associated

with a variety of malformation syndromes. Almost all cases of isolated hemihyperplasia

are sporadic. A number of possible etiologic factors have been suggested but the cause

remains obscure. Various theories include vascular or lymphatic abnormalities, Central

nervous system disturbances, endocrine dysfunctions and aberrant twinning mechanisms.

Occasionally, chromosomal anomalies have been documented.

HEMIHYPERPLASIA. ENLARGEMENT OF THE RIGHT SIDE OF THE FACE.

HEMIHYPERPLASIA. SAME PATIENT AS DEPICTED IN. WITH ASSOCIATED ENLARGEMENT OF THE RIGHT HALF OF THE

TONGUE .

HEMIHYPERPLASIA. RADIOGRAPH OF THE SAME PATIENT. MANDIBLE AND TEETH ON THE RIGHT SIDE ARE ENLARGED.

PROGRESSIVE HEMIFACIAL ATROPHY:

(ROMBERG SYNDROME; PARRY-ROMBERG SYNDROME)

Progressive hemifacial atrophy is an uncommon and poorly understood degenerative

condition characterized by atrophic changes affecting one side of the face. The cause of

these changes remains obscure. Speculation has considered trophic malfunction of the

cervical sympathetic nervous system. A history of prior trauma has been documented in

some cases although other reports have considered a viral or Borrelia infection .

Usually the condition is sporadic, but a few familial cases have been reported

suggesting a possible hereditary influence, many investigators believe that hemifacial

atrophy represents a localized form of scleroderma.

PROGRESSIVE HEMIFACIAL ATROPHY. YOUNG GIRL WITHRIGHT-SIDED FACIAL ATROPHY.

SEGMENTAL ODONTOMAXllLARY DYSPLASIA

(HEMI MAXILLOFACIAl DYSPLASIA):

Segmental odontomaxillary dysplasia is a recently recognized

developmental disorder that affects the jaw and (sometimes) the

overlying facial tissues. The cause is unknown clinically. It is

frequently mistaken for craniofacial fibrous dysplasia or hemi

facial hyperplasia, but it represents a distinct and separate entity.

CROUZON SYNDROME (CRANIOFACIAL DYSOSTOSIS):

Crouzon syndrome is one of a rare group of syndromes

characterized by craniosynostosis, or premature closing of the

cranial sutures.

CROUZON SYNDROME. OCULAR PROPTOSIS AND MID FACE HYPOPLASIA.

APERT SYNDROME :

• Like Crouzon syndrome

• Apert syndrome is a rare condition that is characterized by

craniosynostosis.

• It occurs in about I of every 65,000 to 160,000 births

• caused by a mutation in the fibroblast growth factor receptor 2

(FGFR2) gene.

• Although it is inherited as an autosomal dominant trait, most

cases represent sporadic new mutations, often associated with

increased paternal age.

APERT SYNDROME. SYNDACTYLY OF THE HAND.

APERT SYNDROME. RADIOGRAPH SHOWING "MIDFACE HYPOPLASIA

APERT SYNDROME. ABNORMAL SHAPE OF THE MAXILLA,WITH SWELLINGS OF THE POSTERIOR LATERAL HARD PALATE, RESULTING IN PSEUDOCLEFT FORMATION.

MANDIBULOFACIAL DYSOSTOSIS :

(TREACHER COLLINS SYNDROME)

Mandibulofacial dysostosis is a rare syndrome

• defects of structures derived from the first and second branchial

arches.

• It is inherited as an autosomal dominant trait

• occurs in around 1 of every 25,000 to 50,000 live births.

MANDIBULOFACIAL DYSOSTOSIS. PATIENT EXHIBITS A HYPOPLASTIC MANDIBLE, DOWNWARDSLANTING PALPEBRAL FISSURES, AND EAR DEFORMITIES.