Occurrence of hepatocellular carcinoma in wild pejerrey Odontesthes bonariensis (Teleostei, Atherinidae)

In non-infectious diseases in fish, neoplasms are of great interest to pathologists because of their similarity to those found in other vertebrates, some of which are generated by similar carcinogens, such as hepatocellular carcinoma (HCC), induced by chlorinated compounds, algae toxins, and mycotoxins. We have studied 100 specimens of Odontesthes bonaerensis coming from a highly eutrophic lake, San Roque Lake, in Argentina. Hepatomegaly was macroscopically observed in 24 specimens, with external irregular nodular lesions, necrotic, and hemorrhagic areas. The neoplasms were classified according to the WHO for human HCC, in which 20 neoplasms presented a histopathological pattern of the conventional HCC type. Among the neoplasms, four presented a histopathological pattern of sarcomatoid HCC. In the immunohistochemistry, both Hep Par 1, CD34, CD133, and S100 antibodies were positive in all types of HCC and the transmission electron microscopy analysis revealed an ultrastructure similar to that described in the literature for mammalian and human HCC. The etiology of these HCC could not be confirmed, but taking into account the chronic presence of cyanobacteria with frequent algal blooms, we suggest that they are responsible for these neoplasms, especially considering the hepatic carcinogenic activity of algae peptides such as microcystin.