Odontogenic keratocyst/keratocystic odontogenic tumour: developmental, from dental lamina, genetic factor, enzymatic activity, 60% 10-40 yrs, male, mand 60-80%, antero-posterior radiolucency, multilocular, slow, thin fibrous wall w 6-8 cell layers stratiified squamous epithelium w flattened parakeratin w corrugation, basal cell layer palisaded layer cuboidal cells, enucleation but not easy due to thin friable wall, satellite cyst or budding, 10% multiple OKC, ½ associated w Nevoid basal cell carcinoma syndrome (rare autosomal dominant, mutated PTCH, multiple BCC’s, young, OKC, satellite cysts, skeletal abnormalities, bifid ribs, incr cranial circumference, ovrian fibroma, intracranial calcification), multiplicity when associated w NBSCCS, incomplete removal cyst lining, new KCOT from satellite cysts, de novo occurrence (multilocularity); marsupialisation. used to be neoplasm bc genetic: tumour supressor gene in NBSCCS & sporadic KCOT on 9q22 chromosome, normal functioning PTCH lost. Lysis of collagen cyst wall, resorption, bone expansion, aspirate (keratin squames), keratinised stratified squamous epithelium, flat basal layer, no rete ridges, darkly stained, corrugated w parakeratin, proteinaceous, satellite cysts in wall. Gorlin & Goltz