Mucocutaneous Squamous Cell Carcinoma in a Yucatan Minipig.

Minipigs are commonly utilized in dermal toxicology studies, necessitating documentation of background findings, including neoplastic lesions. We describe a case of a Yucatan minipig with a squamous cell carcinoma at the mucocutaneous junction of the lip. The neoplasm appeared grossly as a slightly raised area of skin with ulceration. Histologically, there were nests and trabeculae of neoplastic squamous epithelial cells undergoing keratinization. Multifocally, rafts of these cells were within lymphatic vessels. Squamous cell carcinoma has not previously been reported in Yucatan or other laboratory minipigs, however, has been reported uncommonly in nonlaboratory pot-bellied pigs. Although squamous cell carcinoma has been associated with ultraviolet exposure or papillomavirus in various species, this was unable to be confirmed in this case.