Abstract

A fetal rhabdomyomatous nephroblastoma is considered to be a predominantly monophasic mesenchymal variant of Wilms' tumor, which acts less aggressively than a conventional Wilms' tumor despite its much larger size. Bilaterality of this tumor in a nine month-old girl, however, may negatively affect the overall prognosis. A radical nephrectomy for bulky masses in the left kidney and a partial nephrectomy for right kidney with five small tumor masses was performed at the same time. Two small tumor masses in the upper part of right kidney were left behind because of preserving minimal renal functional capacity. Pathological study revealed a mixed type of nephroblastoma which was composed predominantly of mesenchymal components with fetal rhabdomyomatous differentiation. After post-operative chemotherapy with vincristine, actinomycin D and adriamycin, and radiotherapy(2,130 rad), residual tumor masses became a single tumor 5 cm in diameter and well demarcated, which was resected at 15 months after first operation when the size and renal function of remained right kidney was appropriate to resect out the residual tumor. The tumor resected out at second operation was entirely composed of scattered differentiated fetal skeletal muscle cells in the fibrovascular tissue. Only a few entrapped epithelial components were seen but no blastemal cornponents were present. Follow up abdominal CT and ultrasonographic examinations revealed no evidence of tumor recurrence. The girl has developed normally without disease.

• Keywords: Wilms' tumor;Fetal rhabdomyomatous differentiation;Bilaterality;Chemotherapy;Radiation therapy