Fibronectin glomerulopathy

Abstract

Fibronectin glomerulopathy occurs between the second and fifth decades of life in most patients, and it is known to be slowly progressive with mild proteinuria leading to kidney failure. The case of a 78-year-old woman with a rapid course of nephrotic syndrome due to fibronectin glomerulopathy is reported. She had proteinuria that rapidly increased to 6.8 g/day in a month and microscopic haematuria. A renal biopsy specimen showed lobular glomerulopathy and membranoproliferative glomerulonephritis-like lesions on light microscopy. There was scanty staining for immunoglobulins and complement. Electron microscopy revealed granular deposits with fibril formation. Immunohistochemistry of the fibronectin showed intense staining in the mesangium and peripheral loop. Therefore, this case was diagnosed as fibronectin glomerulopathy. The kidney function was rapidly decreasing, necessitating haemodialysis 2 months after renal biopsy. It is important to consider fibronectin glomerulopathy in the differential diagnosis of nephrotic syndrome in older people.

Keywords: fibronectin glomerulopathy; haemodialysis; nephrotic syndrome.

Fig. 1.

(A) Haematoxylin and eosin-stained section showed massive, homogeneous, eosinophilic deposits in the mesangium space with formation of a lobular shape (×300). (B) PAS stain. Capillary walls were with double contour (arrows) and almost all glomeruli had numerous PAS-positive deposits (arrowheads) in the mesangium space and between double contour capillary walls (×300). (C) Periodic acid silver methenamine stain. There were silver methenamine stain-negative and PAS-positive materials (arrows) in the mesangium space (×300). (D) Electron micrograph showed faint deposits in the mesangium space (arrows), not the typical electron-dense deposits, but granular deposits with focal fibril formation (×2800). (E) Electron micrograph at high magnification (×60 000). The deposits had fibrillary substructure, with randomly arranged, 12–14 nm fibrils. They had no central core. (F) Immunochemistry for plasma fibronectin showed intense staining in the mesangial and peripheral loop (×300).