Fetal rhabdomyomatous nephroblastoma: report of 14 cases confirming chemotherapy resistance.

The authors retrospectively reviewed their experience with 14 cases of fetal rhabdomyomatous nephroblastoma (15.6% of all renal tumors seen in the 1984-1998 period), analyzing the diagnostic and treatment approach as well outcome. Mean age at presentation was 27 months; 10 (71%) patients were younger than 36 months (5 of these were less than 12 months) at diagnosis. Three patients had bilateral tumors. One case was extrarenal. Nine patients received preoperative chemotherapy after fine-needle aspiration biopsy. The response was null in five children and mild in three; in the remaining one the tumor increased in size. The only patient showing greater than 50% tumor shrinkage was the one treated with radiotherapy. Postoperative treatment according to staging followed the SIOP protocol. In the follow-up (mean 59.5 months) of 12 patients, 6 were in stages 1-2: 4 are alive and free of disease and 2 died (one due to intractable local recurrence and the other in complete clinical remission). All six patients presenting in advanced stages died (four due to disease progression and two due to complications while in complete clinical remission). Patients with fetal rhabdomyomatous nephroblastoma presenting with distant metastatic disease and high stage have unfavorable outcomes, confirming data from the literature indicating that chemotherapy is not as effective as in other variants of nephroblastoma. New protocols are needed to overcome this situation, for which surgery appears the only truly effective option.