A gross and light microscopic study of three neoplasms in farmed <i>Clarias gariepinus</i> and its hybrid

Abstract

There are only a few reports of neoplasms and associated pathologies in teleosts. Three different tumours observed in three different fishes were examined grossly and histologically. In the first C. gariepinus, a large irregular, bristly, pinkish mass was observed to be protruding from the oral cavity. Histopathology of the mass revealed numerous denticles and an abundant fibrovascular stroma. Histopathologically, the tumour was diagnosed as a compound odontoma. In the second C. gariepinus, numerous pale yellow to whitish nodules were observed in the liver. Histopathology of the tumours revealed numerous atypical hepatocytes growing in thick trabeculae within nodules compressing adjacent normal hepatocytes. Individual hepatocytes were pleomorphic, large and vacuolated. The cytoplasmic vacuoles frequently contained globular hyaline bodies. These findings prompted a diagnosis of hepatocellular carcinoma. The ovaries of the female hybrid-Clarias gariepinus x Heterobranchus. Longifilis, were observed to be severely distorted by numerous whitish, irregular, nodules. Histopathologically, the tumour revealed sheets and nests of oval to round cells split into lobules by a fibrous stroma. Each cell possessed scanty to moderately abundant eosinophilic to amphophilic cytoplasm, hyperchromatic round to oval central nucleus with coarse chromatin and multiple nucleoli. Mitotic figures were frequently observed. The tumour was presumptively diagnosed as a dysgerminoma. The aetiologies of these tumours were not determined.

Keywords: neoplasm, fish, histopathology, dysgerminoma, odontoma, carcinoma