Flow cytometric analysis of nephroblastomas and related neoplasms

A total of 59 cases of nephroblastoma and related neoplasms were studied by flow cytometry of paraffin-embedded tissue. According to clinical prognosis, cases were subdivided into three groups: Group 1 (low risk) consisted of congenital mesoblastic nephroma (n = 13) and cystic, partially differentiated nephroblastoma (n = 2). Group 2 (intermediate risk) comprised the various subtypes of "typical" nephroblastoma (n = 24) including cases of fetal rhabdomyomatous nephroblastoma (n = 4). In group 3 (high risk) there were cases of anaplastic nephroblastoma (n = 3), clear cell sarcoma of the kidney or "bone metastasizing renal tumor of childhood" (n = 7), and malignant rhabdoid tumor of the kidney (n = 6). The three clinically different groups of tumors also varied in the proportion of cases with aneuploid tumor DNA stemlines, in S-phase fractions, and in proliferation indices (PI = S + G2 + M). Group 1 was generally characterized by a small number of cases with aneuploid tumor DNA stemlines and low values for S-phase fractions and PI, whereas Group 3 showed the largest number of cases with aneuploid tumor DNA stemlines and high values for S-phase fractions and PI. Group 2 was in between. It is concluded that flow cytometry on paraffin-embedded tissue from pediatric tumors may be a useful adjunct in determining prognosis, and that the subdivision of nephroblastomas and related neoplasms into three prognostically different groups is warranted.