Epithelioid leiomyosarcoma in the visceral peritoneum of an American badger (Taxidea taxus).

A 12-year-old female American badger was presented to the Taipei city zoo veterinary ward with anorexia and weakness. Treatments were ineffective, and the badger died of chronic interstitial nephritis and uremia. At necropsy, numerous firm white nodules, measuring 0.5-2.0 cm, were present on the surface of the liver, stomach, spleen, small intestine, pancreas, and diaphragm. Most nodules were encapsulated and well demarcated from the organs to which they were attached. A poorly demarcated mass, measuring 0.5 cm in diameter, had invaded the hepatic parenchyma and appeared to be the origin of all the nodules derived by transcavitary implantation. Histologically, the nodules contained primarily oval or spindle-shaped cells, typical of smooth muscle cells, forming alternating bundles attached to the surface of the various organs. In some nodules, aggregates of individual polyhedral to round cells with round to oval centrally located nuclei and abundant eosinophilic cytoplasm, typical of smooth muscle origin, were noted. Zones of subcapsular necrosis and multifocal necrosis were also observed in some nodules. Tumor cells stained positively for alpha-smooth muscle actin and vimentin and negatively for desmin, cytokeratin, estrogen, and progesterone receptors. This tumor is similar to but distinguishable from the "disseminated peritoneal leiomyomatosis (DPL)" found in women.