Carcinoma Cuniculatum of Mandible Masquerading as Odontogenic Keratocyst: Challenges in the Histopathological Diagnosis.

Carcinoma cuniculatum is a locally aggressive, low-grade variant of squamous cell carcinoma. Though primarily a tumour of the skin, it has also been found to be arising from various mucosal surfaces including oral mucosa. When it occurs in the mandible it starts as a mucosal lesion which progressively invades the jaw and destroys the underlying bone, often presenting as a cystic lesion. With only around 30 cases reported in the mandible, this entity remains an elusive one for the pathologist and all except a few cases reported so far, had been misdiagnosed initially. The delay in the diagnosis is a major concern as it results in further progression of the disease with extensive involvement of bone and associated soft tissue structures. The aim of this article is to discuss the histopathological challenges faced in arriving at the diagnosis of a case of carcinoma cuniculatum involving the mandible. Owing to its overlapping clinico-pathological characteristics with odontogenic keratocyst the lesion has been misdiagnosed initially resulting in inadequate management, leading to multiple recurrences and unexpected complications. As a few cases like the present one had been erroneously diagnosed as odontogenic keratocyst previously, it becomes important to identify the varied clinical presentation and unique histopathological characteristic of carcinoma cuniculatum of mandible to help us in recognizing this often-missed entity at an earlier stage, so that it can be managed effectively.