FLOW CYTOMETRIC STUDIES OF WILMS-TUMORS

A total of 39 Wilms' tumors and related nephroblastomas were analyzed retrospectively by flow cytometry of paraffin embedded tissue. The pro liferation index (PI) and the DNA index (DI) were calculated in euploi d and/or aneuploid tumors. According to clinical prognosis the patient s were subdivided into three groups: Group 1: Low risk group (cystic, partially differentiated nephroblastoma n = 4, congenital mesoblastic nephroma n = 2). Group 2: Standard risk group (typical nephroblastoma n = 22, fetal rhabdomyomatous nephroblastoma n = 1). Group 3: High ris k group (anaplastic tumors n = 4, clear cell sarcoma n = 5, malignant rhabdoid tumor n = 1). There was a significant increase in proliferati ve activity between the groups with low and intermediate degrees of ma lignancy. In addition a clear link appeared between aneuploidy and ris k group. The study shows that prognostic criteria cannot be based on t he DNA content or proliferation index alone. In case of tumors which a re difficult to classify histologically, such as nephroblastoma rich i n blastema, flow cytometric measurements can be very helpful as an add itional criteria for tumor grading.