FIBRILLARY RENAL DEPOSITS AND NEPHRITIS

  • 1 January 1983
    • journal article
    • research article
    • Vol. 113  (3) , 279-290
Abstract
Patients 8 whose glomeruli contain abundant fibrils in their mesangial matrix and basement membranes were studied. Although the location of these fibrils is very similar to that of amyloid, they are about twice the size of amyloid fibrils, averaging 20 nm in width, and fail to react as amyloid does with special stains. Immunofluorescence-microscopic studies are usually positive with antiserums to IgG, often IgM, and in some cases IgA, and also .kappa. and .lambda. light chains, [complement] C3 and C4. The fibrils are associated with diffuse mesangial widening and increased mesangial matrix strands. Although peripheral glomerular capillary walls appear to be spared initially, their eventual involvement leads to glomerular capillary collapse and glomerular obsolescence. Crescent formation occurred in 5 cases, focally in 3 and diffusely in 2. Tubular basement membrane involvement was seen in 1 case. These patients exhibit hematuria, proteinuria, and often hypertension and renal insufficiency. Proteinuria was in the nephrotic range in 3 patients in whom involvement of glomerular capillary basement membranes was extensive. Unless EM is applied to renal biopsies, these cases may be considered to represent mesangiocapillary or rapidly progressive glomerulonephritis or amyloidosis. The nature of these fibrils is as yet not determined. It is likely that they have been called atypical amyloidosis in the past.