In the most general sense, fibrillary glomerulopathy is a category of glomerular diseases that is defined by the ultrastructural feature of organized deposits of extracellular, non-branching microfibrils. These diseases share similar morphologic features by light microscopy, but differ in their immunophenotypic and ultrastructural characteristics. By light microscopy fibrillary glomerulopathy demonstrates widened mesangium with cell proliferation and an increase in matrix. Progression to a lobular pattern and to total glomerular sclerosis is frequently seen.
Crescents occur in approximately one-third of cases.
Some patients show mild cellular proliferation and prominent acellular mesangial sclerosis, whereas others have marked capillary wall thickening. Stains for amyloid are consistently negative. Extraglomerular involvement is rare. The most common clinical feature was nephrotic syndrome, however, many patients had concomitant hematuria, renal insufficiency, and hypertension. None of the patients had evidence of extrarenal disease, which is in contrast to immunotactoid GN which has a recognized association with some autoimmune and lymphoproliferative disorders.