Phaeochromocytoma and hepatocellular carcinoma
with nuclear glycogenation of the hepatocytes
in a predatory carp (Chanodichthys erythropterus)
Natsuki Tanaka, Takeshi Izawa, Mitsuru Kawamura and Jyoji Yamate
Laboratory of Veterinary Pathology, Osaka Prefecture University, Osaka, Japan
Nobuyuki Higashiguchi and Chiho Kezuka
Kobe Municipal Suma Aqualife Park, Kobe, Hyogo, Japan
Pheochromocytoma is an endocrine tumour derived from chromaffin cells of the adrenal medulla. Here, we report the first case of pheochromocytoma in fish. A female predatory carp (Chanodichthys erythropterus) aged 27 showed abnormal swimming behaviour, anorexia, and tachypnoea. In the head kidney, a light brown mass was observed. Histopathologically, neoplastic proliferation of the cells with polyhedral, granular, and lightly eosinophilic cytoplasm was observed. Transmission electron microscopy revealed that the neoplastic cells had secretory granules with limiting membrane. We diagnosed the tumour as pheochromocytoma. The fish also had a mass in the liver, diagnosed as hepatocellular carcinoma. Almost all hepatocytes had a prominent vacuole in their nuclei. The nuclei were enlarged and presented signet ring like appearance due to eccentrically located chromatin. In electron micrograph, glycogen granules were observed in the nuclei. Therefore, we speculate that the nuclear vacuolation, called nuclear glycogenation, in the hepatocytes may be caused by diabetes resulting from functional pheochromocytoma.