Focal and segmental sclerosing glomerulopathy (-nephritis).

Abstract

10 out of 44 renal biopsy specimens obtained from patients with focal and segmental sclerosing glomerulopathy (-nephritis) (focal sclerosing lesion, sclerose s. hyalinose segmentaire et focale) were examined with the electron microscope and 11 by immunofluorescence microscopy. Particularly ultrastructural alterations are described in detail. A nephrotic syndrome was observed in 33 (75%), proteinuria in 11 (25%), and erythrocyturia in 21 (48%) patients. As the characteristic glomerular lesion a progressive increase in mesangial matrix material (sclerosis) is found which in the beginning concerns only few glomeruli and within these only a portion of the capillary tuft. The remaining glomeruli histologically show minimal changes. Electron microscopy, however, reveals these glomeruli as pathologically altered, too, indicating that the underlying mechanism is a diffuse one. Progression of sclerosing processes finally results in complete sclerosis of more and more capillary loops and glomeruli, respectively. Lightmicroscopically identifiable PAS-positive hyaline deposits were present in about 80%, thus representing an important diagnostic tool. Electron dense deposits, identical with typical immune deposits, are a regular finding in sclerosing areas and very rarely occur in minimally changed glomeruli, too. Immunofluorescence microscopy reveals a corresponding segmental deposition pattern of mostly IgM and C3 globulins. These findings are discussed with regard to an immune pathogenesis of the focal and segmental lesion.