Carcinoma cuniculatum in maxillary gingiva mimicking verruciform xanthoma: a case report.

Carcinoma cuniculatum (CC) is a rare and well-differentiated clinicopathological variant of squamous cell carcinoma (SCC) that is not common in head and neck. It is defined histologically by the infiltrative pattern of a deep, broad, and complex proliferation of stratified squamous epithelium with keratin cores and keratin-filled crypts. It has a propensity for local invasion and rare metastasis. This case report describes a 39-year-old man who was referred to our hospital with painful swelling in the right maxillary gingiva for 1 month and restriction of mouth opening for 1 week. Two biopsy examinations were negative for the diagnosis of malignancy, and the patient was misdiagnosed with verruciform xanthoma before an accurate diagnosis of CC. The biopsy reports were not in line with the imaging findings and clinical manifestations. Finally, he was diagnosed based on the combination of clinical manifestations and the pathological findings. Our case report provided a thorough clinical and histopathologic case of CC in maxillary gingiva, together with a brief review of the literature. In addition, we highlighted the difficulties in arriving at this uncommon diagnosis, and discussed the diagnosis of CC based on the combination of clinical manifestations and the pathological findings. To our knowledge, this is a very rare case of CC of the gingiva mimicking verruciform xanthoma.