Hepatocellular adenoma in a Eurasian otter (Lutra lutra)

A 7-year-old female Eurasian otter (Lutra lutra) at the Seoul Grand Park, Korea, died after displaying depression, anorexia, weight loss and rough skin for several days. At necropsy, a solitary friable round mass, which was approximately 12 x 9 x 5 cm and mottled dark red and yellow, was found bulging from the right hepatic lobe. Microscopically, the nonencapsulated, poorly circumscribed mass was composed of solid sheets of neoplastic hepatocytes. In addition, numerous small tan foci, ranging from 0.5 to 1.0 cm in diameter, were evenly scattered throughout the pancreatic tissue. These foci were found to be nonencapsulated, well-demarcated hyperplastic nodules of the exocrine pancreatic gland. We observed neither intrahepatic nor extrahepatic metastases. Based on the gross and microscopic changes, we diagnosed the animal as having a hepatocellular adenoma accompanied by exocrine pancreatic nodular hyperplasia.