Membranous glomerulopathy with superimposed pauci-immune necrotizing crescentic glomerulonephritis

Anti-Phospholipase A2 Receptor in Nonlupus Patients with Membranous Nephropathy and Crescents

Introduction

Anti-phospholipase A2 receptor (PLA2R) is detected in approximately 70% of biopsies of "primary" membranous nephropathy (MN). Crescents in MN in nonlupus patients suggest additional injury, such as antineutrophil cytoplasmic antibody (ANCA) or anti-glomerular basement membrane (anti-GBM)-associated glomerulonephritis and are postulated to reflect injury by a mechanism that unmasks cryptic epitopes leading to the second autoantibody.

Methods

We studied PLA2R staining in nonlupus patients with MN and crescents. Native renal biopsies in 16 nonlupus patients with MN and crescents were stained for PLA2R.

Results

The patients included 5 women and 11 men, with mean age 61 years and elevated serum creatinine (mean 4.68 mg/dL). Hematuria and proteinuria (mean 4.97 g/day) were documented in 13 patients. Two patients had positive serum anti-GBM antibody. Nine of 11 patients tested for ANCA were positive, with p-ANCA (n = 4), c-ANCA (n = 2), or both (n = 1), with 2 not specified. On average, 27% of glomeruli had crescents. One patient had an initial biopsy with MN, 4 years later had MN with crescent, and 7 years later had rebiopsy with persistent MN with crescents. One patient had ANCA-associated vasculitis, and 5 years later had MN and crescent. The remaining 14 patients had concurrent diagnoses of MN and crescents. PLA2R was positive in 5 cases, 3 with ANCA positivity, 2 with unknown ANCA status, and none with anti-GBM disease. The patient with initial MN preceding crescent was PLA2R positive; the patient with initial ANCA-associated vasculitis preceding MN was PLA2R negative.

Conclusions

Most patients (64%) presented with concomitant MN and crescents, with rare occurrence of an initial disease process followed later by the second injury. PLA2R was positive in 31% of patients, suggesting most are secondary MN. Further study to determine the cryptic epitopes may shed light on the triggering mechanisms for these rare but unlikely coincidental glomerular injuries.

Membranous Nephropathy with Rapid Progression

We report a 49-year-old man with microscopic hematuria, subnephrotic proteinuria, and rapidly progressive renal failure. His biopsy had features of PhosphoLipase A2 Receptor (PLA2R) positive membranous nephropathy with circumferential cellular crescents. Further work-up revealed IgG antiGlomerular Basement Membrane (anti-GBM) antibody titer of 188 U/mL (normal <7 U/mL). A final diagnosis of membranous nephropathy with anti-GBM disease was made. These two distinct pathological entities can occur together resulting in significant morbidity and mortality unless diagnosed early and treatment initiated promptly. Outcomes have been poor, given the nonspecific presentation and delay in diagnosis.

Pauci-Immune Necrotizing and Crescentic Glomerulonephritis with Membranous Lupus Nephritis, Fifteen Years after Initial Diagnosis of Secondary Membranous Nephropathy

Renal involvement in systemic lupus erythematosus (SLE) is usually immune complex mediated and may have multiple different presentations. Pauci-immune necrotizing and crescentic glomerulonephritis (NCGN) refers to extensive glomerular inflammation with few or no immune deposits that may result in rapid decline in renal function. We report a case of a 79-year-old Hispanic male with a history of secondary membranous nephropathy (diagnosed by renal biopsy 15 years previously) who was admitted with acute kidney injury and active urinary sediment. P-ANCA titers and anti-myeloperoxidase antibodies were positive. The renal biopsy was diagnostic for NCGN superimposed on a secondary membranous nephropathy. A previous diagnosis of SLE based on American College of Rheumatology criteria was discovered via Veteran's Administration records review after the completion of treatment for pauci-immune NCGN. ANCAs are detected in 20–31% of patients with SLE. There may be an association between SLE and ANCA seropositivity. In patients with lupus nephritis and biopsy findings of necrotizing and crescentic glomerulonephritis, without significant immune complex deposition, ANCA testing should be performed. In patients with secondary membranous nephropathy SLE should be excluded.

Membranous Nephropathy With MPO-ANCA-Associated Crescentic GN

Introduction:

Antineutrophil cytoplasmic antibodies (ANCA)-associated glomerulonephritis (GN) is characterized by necrotizing and crescentic GN with paucity of immunoglobulin (Ig) and complement deposition, which is also known as pauci-immune crescentic GN. Membranous nephropathy (MN) is characterized by the formation of subepithelial immune deposit with resultant changes in glomerular basement membrane (GBM), most notably spike formation.

Case Presentation:

A 48-year-old man presented with marked proteinuria, hypoalbuminemia, and renal dysfunction with positive results for myeloperoxidase (MPO) and ANCA. Renal biopsy revealed crescents and thick GBM with subepithelial spikes along with IgG deposition on immunofluorescent staining. The condition was diagnosed as MN with MPO-ANCA-associated crescentic GN. He was treated with intravenous methylprednisolone and cyclophosphamide. After one-month follow-up, antibody level and renal function did not improve.

Conclusions:

Coexistence of MN with MPO-ANCA crescentic GN is very rare and should be managed aggressively.