Nonfamilial polycystic kidneys without enlargement.

7 middle-aged males with bilateral, polycystic, nonfamilial kidneys without enlargement are described. The histological examination revealed multiple cysts of varying sizes and changes such as in interstitial nephritis. 6 of the patients had hematuria and/or calculi in the urinary tract. The etiology of the cysts is not clear. The picture does not conform to that of congenital cystic kidney. The cysts might possibly be a final phenomenon in contracted kidneys, so-called acquired cystic disease, but it should be noted that in 4 of the 7 cases the cystic degeneration was demonstrated log before the uremia appeared. Another possibility is that the cystic transformation described here might be attributed to a specific type of interstitial nephritis.