A case of medullary sponge kidney (Cacchi-Ricci disease) mimicking a renal mass.

Medullary sponge kidney (MSK) is an uncommon benign congenital disorder, generally asymptomatic. In symptomatic patients the diagnosis is usually made by excretory urography performed in the most frequent complications such as renal stones, urinary tract infections and haematuria. Excretory urography can be very characteristic, showing cystic collections of ectatic collecting ducts like "bunches of grapes" or "bouquet of flowers". When haematuria represents the only symptom, and radiographic findings are not characteristic of MSK, the differential diagnosis with a renal tumor can be very difficult. We report a case of MSK that underwent nephrectomy since clinical and radiological features mimicked a renal tumor.