Abstract: TH-PO123

Histopathologic Findings and Mortality in Fibrillary Glomerulonephritis

Session Information

Category: Glomerular

  • 1004 Clinical/Diagnostic Renal Pathology and Lab Medicine

Authors

  • Hallab, Ayman, Indiana University, Indianapolis, Indiana, United States
  • Moorthi, Ranjani N., Indiana University, Indianapolis, Indiana, United States
  • Modi, Jwalant R., Indiana University, Indianapolis, Indiana, United States
  • Phillips, Carrie L., Indiana University, Indianapolis, Indiana, United States
  • Dagher, Pierre C., Indiana University, Indianapolis, Indiana, United States
  • Eadon, Michael T., Indiana University, Indianapolis, Indiana, United States
Background

Fibrillary glomerulonephritis (GN) is a rare glomerular disease with a paucity of literature. We present a retrospective collection of our single-center fibrillary GN experience.

Methods

We reviewed 7,579 kidney biopsies performed at our institution between 2001 and 2015 and identified 51 cases of fibrillary GN. Histopathologic features and clinical variables were recorded from the medical record by a nephrologist. Data is presented as mean (SD). Chi-squared test assessed correlation between histologic and categorical clinical variables.

Results

Fibrillary GN constituted 0.7% of kidney biopsies. Average age at diagnosis was 59.9 (8.8) years. Female to male ratio was 1.4:1 with 77% Caucasian patients.
On light microscopy, mesangial proliferative/sclerosing GN was present in 62% of cases. Membranous (MGN), membranoproliferative GN (MPGN), and endocapillary proliferative GN accounted for 10%, 20%, and 8% of cases respectively. Mesangial changes were present in 92% of cases. Crescents were present in 7 cases (14%). Interstitial fibrosis and tubular atrophy IFTA was mild, moderate, and severe in 30%, 45%, and 21% respectively. The mean glomerular obsolescence was 30%.
Immunofluorescence revealed universal staining for IgG and C3. IgM, IgA, C1q were positive in 56%, 12%, and 16% respectively. No Kappa or Lambda restriction was present. The average positivity (0-4) scale for IgG, IgM, IgA, C3, C1q was 2.6, 0.9, 0.1, 2.7, and 0.2 respectively. The pattern was granular in 38% and smudged in 62%.
Electron dense deposits were seen in 7 of 51 cases (14%), mostly subepithelial. Podocyte effacement, seen in 100% of the cases, ranging from patchy to widespread. The average fibril diameter was 15.5 ± 3.4 nm [9 – 28]. Fibrils were deposited in both mesangium and GBM in 82% of the cases, and in either for the rest.
Mortality was 15.7% (8 of 51). No histopathological features were associated with mortality.

Conclusion

Our fibrillary GN analysis confirms the results of prior cohorts. Histopathological features alone are insufficient to predict mortality. As this disease is infrequently reported, these cases will prove vital to pool with other cohorts in order to correlate pathologic features with outcomes.

Funding

  • NIDDK Support