Oral Carcinoma Cuniculatum: A New Entity in the Clinicopathological Spectrum of Oral Squamous Cell Carcinoma.

Carcinoma cuniculatum is principally recognized as a variant of carcinoma involving foot. The World Health Organization (WHO) recognizes Oral Carcinoma Cuniculatum (OCC) as a distinct and rare clinicopathological variant of Oral Squamous Cell Carcinoma (OSCC). OCC is confused clinically and histologically with Verrucous Carcinoma (VC) and is often misdiagnosed as either VC or OSCC. To best of our knowledge, till date, only 50 cases of this tumour have been reported in oral cavity (including the present case) and only limited number of cases have been reported from Indian subcontinent. Pathognomonic feature of OCC is proliferation of stratified squamous epithelium and its infiltration into underlying stroma forming a complex pattern of keratin cores and keratin filled crypts. These complex crypts give it a likeness of rabbit burrow hence, the name cuniculatum (cuniculatus='rabbit warren'). The report aims to present a case of OCC of mandibular gingiva, discuss its diagnostic features and highlight its differences from VC and OSCC.