[Clear-cell variant of nephroblastoma (clinico-morphological characteristics of 9 cases)].

Nine post-mortem cases included 5 boys and 4 girls at the age from 1 1/2 to 13 years. The ratio right/left kidney was 6 to 3; average tumour weight 780 g, higher than in typical nephroblastoma. Bone metastases were found in 6 cases, the therapy was inefficient. Light-microscopic examination revealed structural polymorphism (typical for nephroblastoma areas, fibroses, hyalinosis, myxomatosis), smooth muscles in 2 cases. Electron microscopy of clear cells revealed fibrillar component developed at a various degree, vacuoles, pynocytosis vesicles, large nuclei with fine structure of chromatin. The results indicate the clear-cell variant of nephroblastoma is a sarcomatoid tumour with characteristic structure and uncommon clinical behaviour which makes necessary a special diagnostic and therapeutical approach.