Renal granulomatoses: a retrospective study of 40 cases and review of the literature.

Renal granulomatoses represent 0.5%-0.9% of nephropathies examined by renal biopsies. Granulomas can be isolated to the kidney or associated with other tissue involvement. We describe 40 consecutive patients with renal granulomatoses, associated with pauci-immune crescentic glomerulonephritis in 2 patients and with vasculitis in another, seen in northeastern Paris hospitals between January 1991 and February 2004. The criterion for inclusion was the presence of 1 or more epithelioid granulomas in the renal interstitium. Our population of 25 men and 15 women had a median age of 53 years. All patients suffered from renal insufficiency with median creatininemia of 236.8 micromol/L (range, 124-805 micromol/L), associated with hypertension (25%), median proteinuria of 0.6 g/24 h (range, 0.08-3.00 g/24 h), microscopic hematuria (15%) and leukocyturia (22.5%). Histologic examination of extrarenal specimens detected granulomas in 82.4% of the bronchial biopsies taken, and in 100% of the 2 skin biopsies, the 2 lymph-node biopsies, and the liver and colon biopsies. The following etiologies were retained: sarcoidosis for 20 (50%) patients, drug-induced for 7 (17.5%), tuberculosis for 3 (7.5%), Wegener granulomatosis for 2 (5%), and leprosy, Mycobacterium avium infection, and Crohn disease for 1 (2.5%) patient each. No etiology could be identified for 5 (12.5%) patients. Treatment must be adapted to the etiology of each case. The renal outcome after treatment was generally favorable, with the estimated median creatinine clearance increasing from 26 mL/min (range, 5.4-80.0 mL/min) to 46.5 mL/min (range, 0-118 mL/min) after a median follow-up of 35.5 months (range, 3-158 mo). Nonetheless, 32 patients had persistent renal insufficiency; 1 required hemodialysis and another underwent renal transplantation. Sarcoidosis and medications are the most common causes of renal granulomatosis. Idiopathic and drug-induced forms do not relapse after treatment discontinuation, and remission persists at long-term follow-up.