Carcinoma cuniculatum in the tongue of a patient with oral lichen planus: Unusual presentation.

Carcinoma cuniculatum (CC) is a rare variant of squamous cell carcinoma (SCC). Only 27 cases have been published in English. A 50-year-old male, who presented a white nodule with erythematous areas, localized in the lateral border of the tongue with 2 months of duration. The patient presents oral lichen planus lesions on the tongue, commissure, and buccal mucosa. The microscopy evaluation of the nodular lesion of the tongue revealed a malignant epithelial neoplasia characterized by cuniculatum architecture, similar in appearance to "rabbit burrows" and the final diagnosis was of CC. The management of CC needs cooperation between surgeons and pathologists to establish a correct diagnosis and treatment. CC is a rare entity and must be recognized by oral pathologist so that it is not misdiagnosed as verrucous carcinoma or oral SCC (OSCC). Regarding prognosis, CC must be evaluated and distinguished from other variants of OSCC.