Fibrillary glomerulonephritis: a report of 2 cases with extensive glomerular and tubular deposits

Deposition of nonamyloid fibrillary material in glomeruli is well known. It is, however, unusual to find these fibrils in the tubular basement membranes and unprecedented to have fibrils of different sizes in the same patient. We present 2 cases with nephrotic range proteinuria with evidence of renal insufficiency. In both cases, strong, polyclonal immunoglobulin (Ig)G with C3 deposits were shown in the glomeruli and along tubular basement membranes. Ultrastructurally, the first case had 28-nm fibrils deposited extensively in the glomeruli and along tubular basement membranes. The second case had 30-nm fibrils in the glomeruli and 15-nm fibrils in the tubules. In both cases, the fibrils did not react with the regular amyloid stains. These findings are used to support the view that fibrillary glomerulopathy is not a disease, but rather the morphologic expression of an etiologically diverse group of diseases as yet incompletely defined.