Clear cell sarcoma of kidney: A mimicker of Wilms' tumor.

The differential diagnosis for an abdominal mass in a 2-year-old child is broad and includes lesions of renal, hepatic, gastrointestinal, adrenal, and lymphatic origins. Of these, Wilms' tumor and neuroblastoma are the most common tumors, where Wilms' tumor represents about 92% of renal masses in children. Non-Wilms' renal tumors, rhabdoid tumors, and clear cell sarcoma of the kidney (CCSK) are uncommon. CCSK constitutes approximately 3% of all malignant renal tumors in childhood. In this report, we present a child presenting with a huge renal mass consistent with Wilms' tumor on computed tomography and initial biopsy. However, the final pathologic diagnosis after resection revealed CCSK.