Incidence of acquired renal cysts in biopsy specimens.

AIMS: This study investigated whether or not acquired renal cysts develop in patients with mild chronic renal failure.
METHODS: A retrospective study was carried out using renal biopsy specimens from 720 patients. A renal cyst was defined as a tubule dilated >200 microm.
RESULTS: Renal cysts were found in 21 of 720 renal biopsy specimens. Serum creatinine of 21 patients with renal cysts was significantly higher than that of 699 patients without cysts (2.59 +/- 2.64 vs. 1.09 +/- 0.79 mg/dl) (p < 0.0001). Poor renal function (serum creatinine >1.6 mg/dl) reveals more cyst formation on biopsy specimens than good renal function (serum creatinine <1.5 mg/dl). Cysts were observed in 11 of 607 (1.8%) patients less than 50 years of age and in 10 of 113 (8.8%) patients over 51 years. To exclude simple cysts which are commonly observed in older subjects, 11 patients under 50 years of age were extensively examined. Mean serum creatinine was 2.98 +/- 3.06 mg/dl (0.7-10.4 mg/dl). These 11 patients revealed low creatinine clearance of 47.5 +/- 25.6 ml/min (5-71 ml/min). Creatinine clearances in 7 patients were 52-71 ml/min (serum creatinine 0.7-2.0 mg/ dl). One of 11 biopsy specimens with cysts was examined by immunohistochemistry on lectin. This specimen was positive for tetragonolobus lectin and negative for peanut lectin, suggesting that the epithelial cells lining the cyst were derived from proximal tubules, unlike those of simple cysts.
CONCLUSION: These results suggest that low normal renal function such as creatinine clearances 52-71 ml/min due to nephron loss is sufficient to induce acquired cyst development in various renal diseases. Copyright 2000 S. Karger AG, Basel