Background

Odontogenic cysts are common cysts occurring in the oral cavity. There are two broad categories. In general, periapical cysts located at the tooth root tip and are associated with a nonvital tooth. Dentigerous cysts surround the crown of an impacted tooth and are associated with a vital tooth.

Inflammatory Cysts	Periapical cysts Paradental cysts
Developmental Cysts	Dentigerous cysts Odontogenic keratocyst Calcifying odontogenic cyst Lateral Periodontal cyst Glandular odontogenic cyst

 

GROSS APPEARANCE/ CLINICAL VARIANTS	CHARACTERIZATION
INFLAMMATORY
PERIAPICAL CYST	Also known as radicular cyst, apical periodontal cyst, or lateral radicular cyst Trauma or dental caries causes necrosis of the dental pulp allowing inflammatory mediators to exit through the apical foramen leading to granulation tissue in the apical periodontal connective tissue Causes proliferation of epithelial rests of Malassez and cyst formation
PARADENTAL CYST	Also known as inflammatory paradental cysts, mandibular infected buccal cyst, or buccal bifurcation cyst Occurs buccal and distal to a mandibular molar within 2 years after eruption of the tooth Inflammation induces odontogenic epithelium
DEVELOPMENTAL
DENTIGEROUS	AKA follicular cyst Should never diagnose unless there is an associated impacted tooth
ODONTOGENIC KERATOCYST	AKA primordial cysts, parakeratinized odontogenic cyst, or OKC May be associated with basal cell nevoid syndrome Unilocular cyst occurring between or apical to teeth Multilocular cyst frequently in posterior mandible Little jaw expansion Radiographs reveal edge effect with scalloped periphery with incomplete septation
CALCIFYING ODONTOGENIC CYST	AKA Gorlin cyst, COC Most are intraosseous but occasional extraosseous (peripheral or gingival) lesions occur
LATERAL PERIODONTAL CYST	AKA LPC 0.5-1 cm unilocular cyst between tooth roots in the premolar/canine region of the mandible Associated teeth are vital Extraosseous analogue is gingival cyst of the adult occurring in the buccal gingiva of the premolar area of the mandible Multicystic intraosseous LPCs are botryoid odontogenic cysts and may recur following currettage
GLANDULAR ODONTOGENIC CYST	AKA sialo-odontogenic syst, GOC Large multilocular cyst in anterior mandible

 

HISTOLOGICAL TYPES	CHARACTERIZATION
INFLAMMATORY
PERIAPICAL CYST	Thin nonkeratinized stratified squamous epithelium with slender interconnecting rete processes, exocytosis of neutrophils, and granulation tissue Lining may have mucous cells and Rushton bodies (intraepithelial curvilinear eosinophilic hyaline bodies) and occasional keratinization
PARADENTAL CYST	Histologically identical to periapical cyst
DEVELOPMENTAL
DENTIGEROUS
ODONTOGENIC KERATOCYST	Resembles steatocystoma simplex with corrugated surface Basal layer with palisaded columnar cells with hyperchromatic nuclei Parakeratotic cells present on luminal surface
Orthokeratinized odontogenic cyst	Identical to epidermal inclusion cyst with orthokeratin and a granular layer
CALCIFYING ODONTOGENIC CYST	Ghost cell keratinization in lining epithelium and may be found in connective tissue wall with foreign body giant cell reaction
LATERAL PERIODONTAL CYST	Thin nonkeratinized epithelium with polygonal to flattened squamous cells May have intraepithelial nodular aggregations of polygonal cells with clear cytoplasm Connective tissue may have islands of clear cells or nests of squamous odontogenic epithelium (dental lamina or rests of Serres)
GLANDULAR ODONTOGENIC CYST	Surface columnar to cuboidal cells with eosinophilic cytoplasm with rounded apices and intraepithelial lumina Mucous cells and ciliated cells Intraepithelial spherules of concentrically whorled keratinocytes

 

DIFFERENTIAL DIAGNOSIS	KEY DIFFERENTIATING FEATURES
Hyperplastic dental follicle	Thickness of the membranous connective tissue wall is >3mm Thickened normal dental follicular tisssue
Dental papilla	0.7 cm translucent white button-like nodule of myxoid tissue associated with an incompletely developed third molar with little or no evidence of root formation
Pericoronitis	Inflammation in soft tissue around the crown of an impacted or erupting mandibular third molar

 

PROGNOSIS AND TREATMENT	CHARACTERIZATION
PROGNOSTIC FACTORS
RECURRENCE	If a cyst recurs, it is one of these three cysts It is always advisable to review the histology of the original cyst For these three entities, curettage is inadequate
Odontogenic keratocyst	43% recurrence following currettage
Unicystic ameloblastoma	Look for palisaded columnar cells in the basal layer with hyperchromatic nuclei polarized from the basement membrane
Glandular odontogenic cyst

Rosai J. Ackerman's Surgical Pathology. Eight Edition. Mosby 1996.
Sternberg S. Diagnostic Surgical Pathology. Third Edition. Lipincott Williams and Wilkins 1999.

Mouth and Oral Cavity

Last Updated 11/29/2001