Collagenofibrotic glomerulopathy with a widespread expression of type-V collagen

Collagenofibrotic glomerulopathy is considered as a form of glomerulopathy in which organized collagen type III progressively deposits. We report a case of this disease with widespread expression of collagen type V. A 65-year-old woman was admitted to our hospital for further evaluation of nephrotic-range proteinuria. The patient had had anemia and hypertension for 9 years, and proteinuria for 3 years. A renal biopsy specimen showed a remarkable mesangial expansion with Congo red-negative and periodic acid-Schiff-positive deposits. At the ultrastructural level, two forms of bundling fibers were found in the mesangium and subendothelial side of the glomerular basement membranes (GBM). The GBM itself appeared normal. Immunohistochemical investigation showed that the glomerular lesions were strongly reactive with both anti-collagen type-III and -V antibodies. Immunoelectron microscopy demonstrated collagen type V in both forms of bundling fibers. Despite therapy, her renal function declined. The clinical course and renal pathology of this case were in accordance with collagenofibrotic glomerulopathy except for the widespread expression of collagen type V. Collagen type V is a fibrillar collagen capable of forming banding fibrils. This report poses the question whether collagen type V accumulates only in this particular case or whether it is a normal component in collagenofibrotic glomerulopathy.