Primary Renal Rhabdomyosarcoma: An Unusual Bone Metastasizing Tumor of Kidney.

Rhabdomyosarcoma (RMS) is one of the common malignant tumors in the pediatric age group. There is only a single case report of primary renal alveolar RMS. Fine needle aspiration (FNA) findings of primary renal RMS has not been reported so far. Hence we present an unusual case of primary alveolar RMS of the kidney. An 11 year old boy presented with an abdominal mass. On FNA a diagnosis of undifferentiated sarcoma and anaplastic Wilms tumor were considered. The tumor was resected and showed histopathological features of alveolar rhabdomyosarcoma. He developed multiple bony metastases and succumbed to the illness despite aggressive chemotherapy. RMS of the kidney should be considered in the differential diagnosis of children with a renal mass, and may have an aggressive clinical course with bone metastases.