Odontogenoc keratocyst

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