Parakeratinized odontogenic cyst/Odontogenic keratocyst
Key features
· 5-11% of jaw cysts
· incident peaks in 2nd and 3rd decades.
· Form intraosseously,most frequently in the posterior alveolar ridge or angle of mandible.mandible 75%,predominantly premolar and molar region
· may grow round the tooth
· Sometimes multilocular radiographically
· Spread extensively along marrow spaces before expanding the jaw
· Frequently recur after enucleation
· Definitive diagnosis only by histopathologically,although clinical and radiographic features may help.
· May be confused with ameloblastoma or with dentigerous cysts radiographically.
· May be part of the basal cell naevus(Gorlin)synndrome
· usually multilocular
Typycal Histological features of odontogenic keratocyst
· Epithelial lining of uniform thickness
· Flat lower border of epithelium
· Clearly defined basal layer of tall cells in parakeratinized cysts
· Thin eosinophilic layer of para keratin
· Cyst lining typically much folded
· Epithelial lining weakly attached to the fibrous wall
· Thin fibrous wall
· Satellite cysts in the wall
· Inflammatory cells typically absent or scanty
Evidance that OKC may be neoplastic
· High proliferative activity of epithelial lining
· Caused by mutation or deletion of PTCH tumor supressor gene
· May contain defects of p16,p53 and other tumor suppressor gene
· Associated with other neoplasms in the basal cell nsevus syndrome
· infiltrative(agressive)growth pattern
· SCC may rearly develop within OKC
· Recurrance
Possible reasons recurrance of OKC
· Thin fragile linings,difficult to enucleate intact
· Finger like cyst extensions in to cancellous bone
· Satellite(daughter) cysts sometimes present in the wall
· More rapid proliferation of keratocyst epithelium
· Formation of additional cysts from other dental lamina remnants(pseudo recurrance)
· Inferior standered of surgical treatment
· possibly a neoplasm
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