Spontaneous intraperitoneal rupture of pyonephrosis in a patient with unknown kidney carcinosarcoma: a case report.

Seventeen cases of peritonitis due to rupture of a pyonephrosis have been reported. The majority of these cases occur secondary to renal stones. Only two cases of ruptured pyonephrosis with concurrent kidney neoplasm have been described and only one of these presented as an acute peritonitis. In this presentation we discuss an unusual case of a 68 year old man with a chronic history of bilateral nephrolithiasis and recent pyonephrosis. He presented acutely with peritonitis and was later found to have a carcinosarcoma of the kidney. The case highlights the importance of recognizing the possibility of underling renal carcinoma in patients presenting with a ruptured pyonephrosis and discuss steps to avoid this serious complication.