Surgical Pathology Criteria–

Odontogenic / Jaw Cysts

Note: 
  • Odontogenic cysts are largely classified based on their location, viability of the associated tooth and clinical setting
    • The principal exception to this is the odontogenic keratocyst, which can occur in any site or setting
      • Unlike most of the other cysts, it has aggressive potential
    • Other accompanying jaw neoplasms must be ruled out
Types of cysts (see Diagnostic Criteria below)
  • Inflammatory (associated with a devitalized tooth)
    • Periapical granuloma
    • Periapical cyst
    • Lateral radicular cyst
    • Residual cyst
  • Developmental /neoplastic (usually associated with a viable tooth)
    • Dentigerous (follicular) cyst
      • Eruption cyst
    • Cysts of dental lamina rest origin
      • Lateral periodontal cyst
      • Gingival cyst of adults
      • Glandular odontogenic cyst
    • Keratotic cysts
      • Odontogenic keratocyst
        • Primordial cyst
      • Orthokeratotic odontogenic cyst
      • Gingival cysts of newborn
    • Calcifying odontogenic cyst
    • Unicystic ameloblastoma
  • Other
    • Nasopalatine duct cyst
    • Stafne bone cyst
    • Oral lymphoepithelial cyst

     

Differential diagnostic approach to major lesions
  • First rule out keratotic, ameloblastic or other neoplastic cysts
  • Associated with an erupted but non-viable tooth, it is probably
    • At the apex
      • Periapical granuloma (no epithelial lining)
      • Periapical cyst
    • At the side
      • Lateral periodontal cyst
    • If cyst recurs where dead tooth was removed
      • Residual cyst
  • Associated with a viable tooth
    • If unerupted
      • Dentigerous/Follicular cyst
      • Eruption cyst if about to erupt
    • If erupted
      • Lateral periodontal cyst
 
Diagnostic Criteria
  • Periapical granuloma
    • Involves the apex (root) of a devitalized tooth
    • Composed of granulation tissue with mixed inflammation
      • Lymphocytes, plasma cells, neutrophils in some cases
      • May have lipid or hemosiderin laden histiocytes and cholesterol clefts
      • Granulomatous inflammation usually not present
      • May have Rushton bodies
        • Eosinophilic, laminated or granular, usually fractured by cutting
        • Irregular shapes – rounded, columnar
        • Trichrome stain bright red
        • May be seen in other cyst types with inflammation
      • Small cellular rests may be entrapped
        • Stimulated by the inflammation, they may form a periapical cyst
  • Periapical cyst (radicular cyst)
    • Common – about half of odontogenic cysts
    • Involves the apex (root) of a devitalized tooth
    • Squamous epithelial cyst forming in the background of a periapical granuloma
      • Epithelium is non-keratinizing squamous
        • Rete ridges usually prominent
        • Frequently scattered mucous cells, rarely ciliated cells
      • Inflammation may be intense, as above for periapical granuloma
    • Cyst may be intact or frequently ruptured
      • If intact, epithelium is flat and smooth where present
      • If ruptured, fragments of cyst wall entrapped in  inflammatory infiltrate
        • Epithelium proliferates with prominent, lace-like rete ridges
    • Benign, infrequent recurrence if removed and tooth dealt with
  • Lateral radicular cyst (paradental cyst)
    • Same as periapical cyst except it involves lateral root surface of devitalized tooth
  • Residual cyst
    • Simply a periapical cyst that remains or recurs after the devitalized tooth is removed
  • Dentigerous cyst (follicular cyst)
    • 20% of odontogenic cysts
    • Cyst involving crown of an unerupted tooth
      • Most commonly 3rd molar and supernumerary teeth
      • Rare with deciduous teeth
    • Intact, non-inflamed cyst lined by thin (2-4 cells thick) stratified squamous epithelium
      • Non-keratinizing squamous epithelium with scattered mucous cells, rarely ciliated
      • Generally lacks rete ridges
    • When inflamed, epithelium proliferates
      • Prominent proliferative interconnected rete ridges
        • May be pseudoepitheliomatous
      • Still non-keratinized
    • Fibrous wall can contain nests and cords of odontogenic epithelium
      • Nests may calcify
    • Recurrences rare following removal
    • Carcinomas and odontogenic tumors may rarely arise in dentigerous cysts
  • Eruption cyst
    • A dentigerous cyst overlying the crown of an erupting tooth
    • Usually ruptures spontaneously with no consequence
  • Lateral periodontal cyst
    • Rare, <2% of cysts
    • Involves side of viable tooth
    • Simple or oligocystic
    • Flattened to cuboidal non-keratinizing epithelium
      • 1-5 cells thick
      • Occasional nodules/plaques in epithelium
        • May bulge into lumen or stroma
        • Frequently contain clear, glycogen rich cells
    • Recurrence unusual
  • Botryoid cyst
    • Same features as lateral periodontal cyst above except:
      • Polycystic
      • Frequently large, crossing midline
      • More difficult to resect, but few recurrences if removed
  • Gingival cyst of adults
    • Rare, <1% of cysts
    • Same features as lateral periodontal cyst above
      • Not attached to tooth
    • Recurrence unusual
  • Glandular odontogenic cyst (sialo-odontogenic cyst)
    • Very rare <<1%
      • May be large and multilocular
    • Lined by stratified epithelium
      • Lining layer is cuboidal or columnar
      • May have mucous cells and ciliated cells
      • Intraepithelial cysts/ducts lined by cuboidal epithelium frequent
      • Lining may have nodules/plaques of clear cells as seen in lateral periodontal cyst
    • 30% recurrence rate
  • Odontogenic keratocyst (keratotic odontogenic tumor)
    • 3-12% of cysts
    • Most important cyst type to recognize – aggressive recurrences and syndrome association
      • May be the presenting feature of nevoid basal cell carcinoma syndrome (Gorlin syndrome)
    • Can occur in any site or situation
    • If not inflamed – uniform stratified squamous epithelium 4-8 cells thick
      • Undulating, “corrugated” parakeratotic layer
      • Lacks rete ridges
      • Prominent basal  palisading with basal cytoplasmic clearing (reverse polarity)
      • Basal separation from stroma frequent
      • Cyst may be filled with fluid or keratin
    • Inflammation may result in thickening with rete ridge proliferation
      • Palisading may be less prominent
      • Giant cell reaction may be prominent
    • Epithelial cell rests frequently in cyst wall
      • May give rise to daughter cysts and dystrophic  calcification
    • Occasional findings
      • Only focal orthokeratosis at most
      • Mucous, ciliated or sebaceous cells
      • Melanocytic pigmentation
      • Involvement by carcinoma is very rare
    • Frequent recurrence (30-60%)
      • Less recurrence if completely removed
      • May take 5-10 years to recur
  • Orthokeratotic odontogenic cyst
    • Rare, about 1% of cysts
    • As above but has a granular layer and orthokeratosis
      • Also lacks prominent basal palisading and clefting from stroma
      • Parakeratosis if present is focal
    • Recurrence is rare
  • Gingival (alveolar) cysts of newborn
    • These are so frequent that they may be considered normal findings
      • Small, white nodules, usually multiple
      • They do not cause discomfort
    • Microscopically they are small keratinous cysts
      • May be ortho- or parakeratotic
    • Usually maxillary, two types
      • Bohn nodules along dental ridge and along junction of soft and hard palate
      • Epstein pearls predominantly midline palate
    • Spontaneously resolve without intervention
  • Calcifying odontogenic cyst (calcifying ghost cell odontogenic cyst, calcifying cystic odontogenic tumor)
    • About 1% of cysts
      • Rare posterior to first molar
    • Palisaded basal cell layer with reverse polarity of nuclei
    • Several layers of stellate ameloblast-like cells
      • Ghost cell keratinization
        • Large anucleate cells with preserved cell borders
        • Frequent dystrophic calcification
          • May elicit a giant cell reaction
      • Dysplastic dentin may be induced in adjacent stroma
    • Frequently associated with unerupted tooth or odontoma
    • May also be associated with other odontogenic tumors
    • Fibrous capsule may contain epithelial rests
    • Recurrence rare unless associated with other tumors
  • Unicystic ameloblastoma
    • Simple cyst lined by stratified cells
      • Palisaded basal cell layer with reverse polarity of nuclei
      • Several layers of edematous,  spongiotic, stellate cells
      • May show surface parakeratosis
      • Large areas may be lined by nonspecific epithelium
    • Ameloblastic epithelium may proliferate and form plexiform intraluminal nodule(s) (intraluminal unicystic ameloblastoma)
      • Same behavior as simple cyst
    • Invasion into the wall of the cyst is not permitted
      • Behaves more like conventional ameloblastoma
    • When defined as above, recurrence is rare
  • Nasopalatine duct cyst
    • In anterior midline of hard palate
    • Variable, often mixed epithelial linings
      • Squamous, cuboidal, ciliated
    • Nasopalatine artery and nerve usually part of resection
  • Stafne bone cyst
    • Concave defect in cortical bone of mandible
    • May contain salivary gland tissue
  • Oral lymphoepithelial cyst
    • Floor of mouth, tongue
    • Lined by keratinized stratified squamous epithelium
    • Lymphoid tissue in wall of cyst

Bibliography

  • Neville B.W., Damm D.D. and Allen C.M., Odontogenic Cysts and Tumors, in Diagnostic surgical pathology of the head and neck, 2nd edition, 2009, D. R. Gnepp, ed., pp 785-838
  • Wright JM, Odell EW, Speight PM, Takata T. Odontogenic Tumors, WHO 2005: Where Do We Go from Here? Head Neck Pathol. 2014 Dec;8(4):373-82. PubMed PMID: 25409849
  • Shear M. Developmental odontogenic cysts. An update. J Oral Pathol Med. 1994 Jan;23(1):1-11. PubMed PMID: 8138974.
  • Regezi JA. Odontogenic cysts, odontogenic tumors, fibroosseous, and giant cell lesions of the jaws. Mod Pathol. 2002 Mar;15(3):331-41. PubMed PMID: 11904346

Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342

Original posting/last update: 12/14/14

 

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