Simultaneous medullary sponge and adult polycystic kidney disease: the need for accurate diagnosis.

Two cases of simultaneous medullary sponge and adult polycystic kidney disease developed in siblings. The diagnoses of polycystic kidneys were made by renal ultrasonography and medullary sponge kidney was diagnosed roentgenographically. The family history was markedly positive for "cystic" disease. Medullary sponge kidney might be a precursor of polycystic kidney disease in some instances, or, more likely, this represents two separate afflictions occurring in the same individuals. When large medullary sponge kidneys are encountered, the possibility of concomitant polycystic kidney disease should be entertained and investigated with a sonogram. While the prognosis of isolated sponge kidney is excellent, polycystic kidney disease eventually leads to hypertension and renal failure.