Extracutaneous mast-cell tumor in the dog.

Three neoplasms of extracutaneous mast-cell origin, arising from the nasopharynx, oral cavity, and hepatopancreatic lymph nodes respectively, were diagnosed in three dogs. The neoplasms had histologic features similar to those of cutaneous mast-cell tumors, but had limited metastasis mostly involving the regional lymph nodes. One dog had a perforating duodenal ulcer, suggesting that duodenal ulcers can occur with extracutaneous tumors as they do with some cutaneous mast-cell tumors in the dog.