Hepatic Tumors in Flatfish from Sivuch'ya Bight (Peter the Great Bay, Sea of Japan)

The livers of six flatfish species from Sivuch'ya Bight were examined histologically for the presence of neoplastic lesions. Out of 120 fish studied, hepatic tumors were found in two individuals: the black plaice Pleuronectes obscurusand the longsnout flounderPleuronectes punctatissimus.Based on presence of tissue and cellular atypism, tumor pearls surrounded by squamous cells, and absence of mucous secretion, the neoplasm in P. punctatissimuswas classified as squamous cell carcinoma. Abnormal growth of fibrous stroma suggests a scirrhous variant of carcinoma. Tumor in P. obscuruswas classified as a hepatocellular adenoma. This is the first information on liver tumors in flatfishes of Sivuch'ya Bight.