Unicystic desmoplastic osteo-ameloblastoma of posterior mandible: Report of rarest of the rare case and review of literature.

Desmoplastic ameloblastoma (DA) is an epithelial odontogenic tumor and a rare variant of ameloblastoma. It was first described by Eversole in 1984. In the World Health Organization (WHO) classification of odontogenic tumors (2005), DA has been considered as a distinct entity from conventional/multicystic ameloblastoma. DA differs strikingly in its clinical, radiological, and histopathological presentation when compared to other variants of ameloblastoma. We report here an extremely rare "Hybrid DA" in a 50-year-old female patient with painless hard swelling involving right posterior mandible with detailed clinical history, an unusual radiographic and histopathological presentation. Histopathology revealed odontogenic epithelium in the form of follicles, ameloblastoma with cystic degeneration, and squamous metaplasia at places and elsewhere there were odosntogenic islands compressed by dense fibrocellular stroma suggestive of desmoplasia along with osseous tissue formation. Also review of the literature and possible explanation of etiopathogenesis of cystic change and osseous tissue formation in DA are discussed.