Histopathological features of keratocystic odontogenic tumor: a descriptive study of 177 cases from a Brazilian population.

The aim of this study was to describe the clinicopathologic features of 177 keratocystic odontogenic tumors (KCOTs) diagnosed in a Brazilian population. A total of 177 KCOTs were reviewed and affected 158 patients with ages ranging from 5 to 79 years (mean age = 32 years) with a slight female predominance. Mandible was the most common affected site (69.3%), and a unilocular radiolucency was the most common radiographic image. Microscopically, all cases showed at least focal areas of classic KCOT, but several histological aspects were also observed, including diffuse and focal epithelial lining hyperplasia (48.6%), epithelial budding (12.4%), reactive cytological alterations (11.3%), dystrophic calcification (7.9%), daughter cysts (7.8%), odontogenic epithelial remnants (4.5%), focal areas of orthokeratinization (2.8%), and ameloblastomatous epithelium (1.7%). These variations may make KCOT diagnosis challenging in some cases, so careful full-sample analysis and knowledge of these uncommon histological features associated with KCOT are essential for correct diagnosis.