Behcet's syndrome and renal involvement: a histological and immunofluorescent study of eleven renal biopsies.

The finding of focal glomerulonephritis in a patient with Behcet's syndrome led us to perform systematic renal biopsies in ten other patients with the disease. None of the patients had symptoms of renal disease. Proteinuria was found in five, two of whom had associated leukocyturia. By light microscopy mesangial and extramembranous glomerular deposits were observed in eight patients. Arterioles in ten patients showed subendothelial and medial hyaline deposits. A granular pattern of fluorescent staining identified the presence of the third component of complement in these deposits. Circulating immune deposits were sought and found in six out of seven patients. The finding of circulating immune complexes and deposition of complement in glomerular and arteriolar tissues supports an immune complex mediated nephropathy and is consistent with the hypothesis of an immunological pathogenesis in Behcet's syndrome.