Fetal rhabdomyomatous nephroblastoma. Report of two cases and review of the literature

Objective: Fetal rhabdomyomatous nephroblastoma is a particular and very rare histologic variety of nephroblastoma. The aim of this work is to study the principal clinic, therapeutic and evolutive characteristics of the fetal rhabdomyomatous nephroblastoma through two personal cases and a review of the literature. Patients and methods: This is a retrospective study of two observations of fetal rhabdomyomatous nephroblastoma treated in the pediatric surgery departement of Monastir (Tunisia) among 47 cases of nephroblastoma. The diagnosis was confirmed in the two cases by the histologic examination. Results: The two patients were a six and a sixteen months old boy and girl. They were admitted for a voluminous mass occupying the left half-abdomen. The radiologic and biologic explorations load, in the two cases, to the diagnosis of left nephroblastoma. After a first chemotherapy that did not induce a reduction of the tumoral volume, a widened left nephrectomy was performed for the two patients. The histologic examination of the two pieces of nephrectomy concluded to a fetal rhabdomyomatous nephroblastoma with existence in the second case of an extension of the lesions to the renal pelvis and ureter in the form of a pseudo-botrydïde tumor. The tumor was classified stage I in the first case and stage II N0 in the second. The treatment was completed by an adapted post operative chemotherapy according to the SIOP 9 protocol. The two patients are currently in complete remission with an overview of six years and half. Conclusion: The fetal rhabdomyomatous nephroblastoma is a special histologic form of nephroblastoma that is characterized by the paucity of pulmonary metastasis, the absence of response to chemotherapy and the possibility of tumoral extension in the renal pelvis and ureter. His prognosis is similar to the classical nephroblastoma. © 2002 Éditions scientifiques et médicales Elsevier SAS.