Spontaneous nephroblastoma in rainbow trout

Objective: To describe a nephroblastoma in a juvenile rainbow trout Oncorhynchus mykiss Method & Materials: The fish were fed with dry pellets. Tissue samples for histological examination of the tumor and organs (kidney, spleen, liver, stomach, gut, brain, muscle and gills) were fixed in 10% neutral formalin, embedded in paraffin and sections were stained with H&E. Results & Conclusion: The total body length of the fish was 140 mm and weight 45 g. The tumor was of a considerable size and weight (28.8 % of the fish’s body weight) which caused lordosis of the host's spine. The tumour's expansive growth pushed the internal organs deep into the abdominal part of the body. The tumor structure comprised 2 components: epithelial and mesenchyme. Its epithelia1 parts prevailed, no other structures (myeloblastic. neuroblastic and cartilaginous) was present. The tumor was a demarcated formation with no hemorrhages, no necroses and metastases that would penetrate into the organs. No haematopoietic tissue and no melanin were detected in the neoplastic tissue. The structure of the tumor corresponds with cryptogenic nephroblastoma. We found no hyperaemia in the tumor, nor any haemorrhage and necrosis. Our finding is another case of absence of metastases in the rainbow trout, which is in contrast with the expenence with nephroblastoma described so far in humans and other vertebrates.

کلیدواژه ها:

Nephroblastoma ، tumor ، rainbow trout ، necrosis ، hemorrhage