Co-occurrence of a metastatic mammary liposarcoma and an ovarian sex-cord stromal tumor in a dog.

Sarcoma arising in the mammary gland is a rare tumor in dogs, and primary liposarcoma with metastatic behavior has never been previously reported among canine mammary tumors. A 14-year old female poodle had a mammary mass diagnosed as pleomorphic liposarcoma. Two years following surgical removal, the tumor recurred in the mammary gland with lymph node metastases. In addition, a sex-cord stromal tumor was identified in the ovary. Immunohistochemistry was performed on both tumors that were positive for oestrogen and progesterone receptors. Moreover, the ovarian tumor was positive for calretinin. This is the first report to the authors' knowledge, of the co-occurrence of a pleomorphic liposarcoma of the mammary gland and an ovarian sex-cord stromal (gonadostromal) tumor in the dog.