Mast Cell Tumors: The Good , the Bad, and the Ugly

MAST CELL TUMORS: THE GOOD, THE BAD, AND THE UGLY

MCTs constitute approximately 20% to 25% of the skin and subcutaneous tumors seen by practicing veterinarians. Brachiocephalic breeds (Boxer, Boston Terrier, Bull Mastiff, English Bulldog) and Golden Retrievers are at high risk for MCTs. MCTs occur either as dermoepidermal masses (i.e., a superficial mass that moves with the skin) or subcutaneous masses (i.e., the overlying skin moves freely over the tumor). Grossly, MCTs can mimic any primary or secondary skin lesion, including a macula, papula, nodule, tumor, and crust. Approximately 10% to 15% of all MCTs in dogs are clinically indistinguishable from the common subcutaneous lipomas. As a rule, an MCT cannot be definitively diagnosed until the lesion has been evaluated cytologically or histopathologically.

Most MCTs are solitary, although multifocal MCTs can occur in dogs. Regional lymphadenopathy caused by metastatic disease is also common in dogs with invasive MCTs. Occasionally splenomegaly or hepatomegaly is present in dogs with systemic dissemination. Given the fact that mast cells produce a variety of bioactive (mainly vasoactive) substances, dogs with MCTs may be evaluated because of diffuse swelling (i.e., edema and inflammation around a primary tumor or its metastatic lesion), erythema, or bruising of the affected area. […]