[A case of nephronophthisis-cystic renal medulla complex]

A 27-year-old man was admitted to our hospital for evaluation of renal function. Several months ago, renal dysfunction was discovered quite by chance. There was no family history of renal disease. On admission, the blood pressure was 140/82 mmHg. Laboratory examinations revealed hemoglobin of 14.4 g/dl; BUN, 37.4 mg/dl; serum creatinine, 2.3 mg/dl. The urinalysis showed specific gravity of 1.005, no proteinuria, no hematuria and no urinary sediment abnormalities. Creatinine clearance was 35 ml/min, and PSP test (15') showed 16%. An ultrasonographic study revealed atrophy of the right kidney and increased medullary echogenicity of the left kidney. A renogram showed non-functioning pattern of the right kidney and markedly impaired pattern of the left kidney. An open renal biopsy was performed on the left kidney. On light microscopy of the biopsy specimen, tubular dilatation, interstitial fibrosis, mononuclear cell infiltration and focal tubular atrophy were observed. No remarkable changes were found in the glomeruli. Electron microscopy revealed thickening of the tubular basement membranes (TBM). The clinicopathological findings of this case were compatible with nephronophthisis-cystic renal medulla complex.