Renal rhabdomyosarcoma in a pancake kidney.

Renal rhabdomyosarcoma (RMS) is a rare pediatric tumor. Pancake kidneys are unusual anatomic anomalies resulting when both upper and lower poles of the embryonic kidney become fused. We report on a 4-year-old boy who was discovered to have a stage 4, group IV renal embryonal RMS arising from a pancake kidney with metastases to the lung, pelvis, and bone marrow. Treatment included multimodal therapy, consisting of neoadjuvant chemotherapy, complete surgical resection, and adjuvant chemotherapy. He remains in clinical remission 7 months after resection.