Primary Intra-Osseous Basaloid Squamous Cell Carcinoma of Mandible: Report of Rare Case with Proposed Diagnostic Criteria.

Basaloid squamous cell carcinoma (BSCC) is a distinctive variant of squamous cell carcinoma (SCC) characterised by nests of basaloid cells. BSCC is an aggressive and rare tumor of head and neck region; and is relatively rare in oral cavity in comparison to SCC. Although, infrequent, but primary intra-osseous SCC (PIOSCC) has been reported in the jaws. There are separate diagnostic criteria for this lesion and a classification for primary intra-osseous carcinoma has been described. No evidence was found in the published literature about primary intra-osseous BSCC (PIOBSCC). We, herein, present a case of giant osteodestructive lesion of the posterior mandible which was diagnosed as PIOBSCC with a correlation of histopathological and immunohistochemical features. As per the best of our knowledge, this is the first case of PIOBSCC of the jaw. There is no diagnostic criterion of PIOBSCC in the literature owing to the extreme rarity of this tumor. A diagnostic criterion is proposed here to make the diagnosis of this tumor easier.