Squamous cell carcinoma of the renal pelvis presenting as hydronephrosis.

Primary malignant tumors of the renal pelvis are relatively rare with squamous cell carcinoma (SCC) accounting for 0.7% to 7%. We present a case of a 58-year-old male with huge hydronephrosis on the left side where histology of the resected specimen showed features of SCC. There was no evidence of renal calculi or other predisposing factors. The case highlights the rarity of the tumor in the absence of calculi, as well as the importance of a careful study of a gross specimen and histologic sections in every case of hydronephrosis.