Pauci-immune crescentic glomerulonephritis: A series of 21 cases

Abstract

Background: Pauci-immune crescentic glomerulonephritis is the most common cause of crescentic glomerulonephritis (CrGN). Patients usually present with rapidly progressive glomerulonephritis (RPGN) with hematuria, proteinuria, and elevated serum creatinine levels. The characteristic feature of pauci-immune CrGN is focal necrotizing CrGN associated with little or no glomerular staining for immunoglobulin (Ig) by immunofluorescence microscopic examination. Most patients (80-85%) with pauci-immune CrGN, including the patients with and without systemic vasculitis, have antineutrophil cytoplasmic autoantibodies (ANCAs). Aims and Objectives: To study and compare the histological and laboratory features of ANCA-positive and ANCA-negative pauci-immune CrGN. Materials and Methods: Patients who were diagnosed with pauci-immune CrGN from January 2012 to May 2015, at BABINA Diagnostics, were included in this retrospective study. The terms pauci-immune and crescentic glomerulonephritis were defined according to standard guidelines. The demographic and laboratory data were extracted from the Laboratory Information System (LIS) for analysis. ANCA tests were performed by both indirect immunofluorescence (IIF) assay (EUROIMMUN, Lubeck, Germany) and antigen-specific enzyme-linked immunosorbent assay (ELISA) (ORGENTEC Diagnostika GmbH, Germany). Renal specimens were evaluated using direct immunofluorescence (for Ig and complement components) and light microscopy using routine and special stains. Results: Four (19%) out of the 21 cases of pauci-immune CrGN were ANCA negative. Acute features on histology were seen more than chronic features than ANCA-negative cases. Conclusion: Among the patients with pauci-immune CrGN, ANCA-negative patients were not rare. Compared with ANCA-positive patients, ANCA-negative patients had a lower percentage of normal glomeruli, more of chronic features, and a higher level of proteinuria.