Therapy and outcome in 51 children with mesoblastic nephroma: a report of the National Wilms' Tumor Study.

Mesoblastic nephroma is a distinctive pathologic renal tumor with unique clinical, therapeutic, and prognostic patterns. This report reviews 51 patients (2.8% of 1905 patients submitted to NWTS with renal tumors) with this diagnosis from the NWTS contrasting this disease entity with Wilms' tumor. There were 33 males and 18 females, predominantly term babies born after uncomplicated pregnancies. The mean age at tumor excision was 3.44 +/- 0.6 mo (one child 9 yr). A palpable mass was the predominant presentation in 48 patients and in addition hematuria (9), hypertension (2), vomiting (3), and jaundice (1) were noteworthy. Diagnostic studies included IVP (49 positive, 2 negative) and ultrasound (15 positive, 1 negative). Adequate operative excision was achieved in 43 of 51 patients while 8 children had local extension and 10 had tumor spillage. Operation alone (23), predominantly since 1978, surgery plus chemotherapy (24), prior to 1978, and surgery, chemotherapy, and radiation therapy (4), prior to 1976, were the modes of therapy. The follow-up ranges from 4 mo to 11.5 yr. Survival was excellent; 50 patients survive (98%), only 1 dying of sepsis. These data suggest that mesoblastic nephroma contrasts with Wilms' tumor in that it occurs in a younger age group, has a benign biologic behavior, and a more favorable outcome. Aggressive multimodal treatment though utilized in the early years of the study is not essential to achieve this outcome.