Fibrillary Glomerulonephritis: A Report of 66 Cases from a Single Institution.
Samih Nasr, Anthony Valeri, Lynn Cornell, Mary Fidler, Sanjeev Sethi, Nelson Leung, Fernando Fervenza. Mayo Clinic, Rochester, MN; Columbia University, New York, NY
Background: Fibrillary glomerulonephritis (FGN) is a rare primary glomerular disease. Most previously reported cases were idiopathic. In order to better define the clinical-pathologic spectrum and prognosis, we report the largest single-center series with the longest follow-up.
Design: The characteristics of 66 FGN patients who were seen at our institution between 1993-2010 are provided.
Results: The mean age at diagnosis was 53 yrs. Ninety-five percent of patients were Caucasian and the female:male ratio was 1.2:1. Underlying malignancy (most commonly carcinoma), dysproteinemia, or autoimmune disease (most commonly Crohn's disease, SLE, Graves' disease, and idiopathic thrombocytopenic purpura) were present in 23%, 17%, and 15% of patients, respectively. Presentation included proteinuria (100%), nephrotic syndrome (38%), renal insufficiency (66%), hematuria (52%), and hypertension (71%). The most common histologic pattern was mesangial proliferative/sclerosing GN (71%) followed by membranoproliferative GN (15%). Endocapillary proliferative GN, crescentic GN, membranous GN (MGN), and diffuse sclerosing GN were rare patterns, seen in 6%, 5%, 2%, and 2% of cases. By definition, the glomerular deposits were Congo-red negative. By immunofluoresence (IF), all 66 cases showed glomerular positivity for IgG and in 11% the deposits were monoclonal. Tubular basement membrane deposits on IF were seen in 14% of cases. On electron microscopy, the fibrillary deposits were seen in the mesangium in 98% of cases and in the GBMs in 85%. In the single case with MGN pattern on light microscopy, the fibrillary deposits were present in the subepithelial zone of the GBMs associated with spike formation, without mesangial deposits. In all 66 cases, the fibrils were randomly-oriented and straight, with a mean diameter of 18 nm (range of means, 9-26 nm). During an average of 52.3 mo of follow-up for 61 patients with available data, 13% had complete or partial remission, 43% had persistent renal dysfunction, and 44% progressed to ESRD. The disease recurred in 36% of 14 patients who received a kidney transplant. Independent predictors of ESRD by multivariate analysis were older age, higher creatinine and proteinuria at biopsy and higher percentage of global glomerulosclerosis.
Conclusions: Underlying malignancy, dysproteinemia, or autoimmune diseases are not uncommon in patients with FGN. Prognosis is poor, although remission may occur in a minority of patients without immunosuppressive therapy. Age, degree of renal impairment at diagnosis, and degree of glomerular scarring are predictors of renal survival.
Category: Kidney (does not include tumors)
Monday, February 28, 2011 1:00 PM
Platform Session: Section H, Monday Afternoon