Analysis of the Neoplastic Nature of Odontogenic Keratocyst and its Comparison with other Selected Benign Odontogenic Tumours: An Immunohistochemical Analysis

Odontogenic keratocyst (OKC) fi rst described by Philipsen in 1956 constitutes approximately 11% of all cysts of the jaws. Adenomatoid odontogenic tumour (AOT) is an uncommon, benign epithelial lesion of odontogenic origin. The aim of this study was to analyse the expression of Bcl-2 in OKC and its comparison with other selected benign odontogenic tumours (OTs). Ten formalin fi xed paraffi n embedded blocks of OKCs, fi ve each of AOT and unicystic ameloblastoma Bcl-2 protein is characterized by its ability to inhibit apoptosis. OKC were characterized by higher expression of Bcl-2 in basal cell epithelium. AOT and unicystic ameloblastoma differed from OKC in a wide spectrum of apoptosis and/or cell cycle-related protein expressions, higher proliferation in the basal cell layer, and vice versa, lower proliferation in the suprabasal cell layer. The solitary OKC seems to be less biologically aggressive and should be classifi ed as a cyst rather than a tumour, means that at least few of OKCs manifests as ordinary cysts. Some of the present study fi ndings could support the theory that OKCs are with high proliferative, probably that these lesions are developmental cysts with some neoplastic properties because of the high intrinsic growth potential. WHO recommends the term KCOT as it better refl ects the neoplastic nature of the lesion; however, this reclassifi cation has not yet been universally accepted.