Malignant pheochromocytoma in a pig.

Endocrine tumors are rarely observed in pigs, and pheochromocytomas have been only punctually described. The current report describes a white and firm, 15-cm in diameter, neoplastic mass located in the adrenal gland with metastasis to regional lymph nodes in a 2.5-year-old sow. The masses had marked desmoplasia that supported a population of polygonal-to-spindle-shaped neoplastic cells arranged into cords and packets within a delicate fibrovascular stroma. Immunohistochemical staining of the tumor was positive for chromogranin and negative for neurofilament protein in adrenal and lymph node masses, which was characteristic of a malignant pheochromocytoma.