Keratocystic Odontogenic Tumor of Buccal Mucosa: A Rare Case Report and Histochemical Comparative Study

Keratocystic odontogenic tumor (KCOT) is a benign intraosseous neoplasm of the jaw occurring most commonly in mandibular ramus molar area with male predilection. Peripheral KCOTs are very uncommon. Here we report a case of keratocyst in buccal mucosa in a 55 years old female patient, the diagnosis of which was based on subjective histological evaluation and further confirmed by immunohistochemical stain and compared its immunohistochemical features with intraosseous KCOT. Intraosseous KCOT and buccal mucosa keratocyst were stained with hematoxylin and eosin, picrosirous red, Ck 17, Bcl 2 and Ki 67, and compared. Keratocyst of buccal mucosa showed positive expression for CK17 and Ki 67, and negative expression of Bcl2. On polarizing microscope, it showed yellowish red birefringence of collagen fibers in connective tissue wall. Keratocyst in the buccal mucosa is rare. Though it mimics intraosseous counterpart histopathologically, the nature of connective tissue and low proliferation index makes it less destructive. Therefore, it requires only conservative excision with follow up.