[Nephroblastoma: clinico-morphological characteristics and problems of classification].

Clinical and morphological examinations were carried out in 159 children with nephroblastoma. A working histological classification of tumors with reference to prognosis is proposed. It includes typical (89 cases) and atypical (23 cases) variants of the tumor. Among typical tumors, those with predominance of nondifferentiated blastema are distinguished. The atypical tumors include tubular fetal rhabdomyomatous, cystic, sarcomatous (rhabdoid, clear cell) variants. A group of tumors with marked therapeutic pathomorphosis (27 cases) is distinguished among unclassified tumors. Unfavourable prognosis in tumors with predominance of undifferentiated blastema, sarcomatous variants, and tumors with marked therapeutic pathomorphosis is indicated. Attention is drawn to increased number of glomerulo-like structures and cell anaplasia as a possible unfavourable prognostic sign.