Abstract

From 2000 to 2012, tissues from 178 meerkats were submitted from zoological collections throughout the continental U.S.A. for histopathologic evaluation. Of these cases, 8 (4.5%) were diagnosed with hepatocellular carcinomas, 2 (1.1%) with hepatocellular adenomas, and 2 (1.1%) with nodular hepatocellular hyperplasia. One case had been previously diagnosed as a hepatocellular adenoma, and was subsequently diagnosed as hepatocellular carcinoma on excisional biopsy 1 yr later. In another case, both a hepatocellular carcinoma and adenoma were identified on distinct liver lobes of the same patient. All individuals were adults ranging in age from 8–13 yr, with a median age of 11 yr. The predominant clinical signs were lethargy, weight loss and palpable abdominal masses. Histologically, hyperplastic lesions exhibited a well-demarcated, nodular appearance, with mild anisokaryosis and anisocytosis, but no identified mitotic figures. Hepatocellular carcinomas were well differentiated, the majority of which were characterized either by a trabecular pattern of neoplastic hepatoid cells or cords and sheets of hepatoid cells, with mild to moderate anisokaryosis, large nucleoli, and no to occasional mitotic figures. Metastasis to the local mesentery was observed in one case, and to the lungs and adjacent thoracic lymph node in another. Based on this report, hepatocellular tumors, in particular, hepatocellular carcinomas appear to occur commonly in the captive meerkat population. These findings may be consistent with low genetic diversity within the captive population or underlying infectious etiology. Further investigation into a possible viral etiology of hepatocellular carcinomas in captive meerkats is being pursued at this time.