First case report of PLA2R-related monotypic (IgG-κ positive) membranous nephropathy concurrent with leukocyte chemotactic factor 2 amyloidosis

Abstract

Background: Membranous nephropathy (MN) is a major pattern of nephrotic syndrome (NS) in adults. Some MN have secondary causes and some may be accompanied with other glomerular diseases. MN patients coexisting with amyloidosis are very rare, and mostly was polytypic MN. Herein, we describe the first report which identifying monotype PLA2R-MN (κ light chain) concurrent with leukocyte chemotactic factor 2 amyloidosis (ALECT2). This rare case highlights the importance of renal pathology for diagnosis.

Case presentation: We describe a case of a 60-year-old male patient with persistent proteinuria and low serum albumin for nine months. No monoclonal component was revealed by serum and urine immunofixation electrophoresis but serum PLA2R antibody was positive. The patient was empirically treated with Leflunomide and Losartan, but edema was not improved. The diagnosis of renal pathology is PLA2R-related monotypic (IgG-κ positive) MN concurrent with ALECT2. Methylprednisolone, cyclosporine A and anticoagulant (rivaroxaban) were prescribed resulting in a complete remission of NS.

Conclusions: MN patients concurrent with ALECT2 presented massive proteinuria or NS. When nephrotic range proteinuria is present in ALECT2, it is important to consider that it may be due to a concomitant underlying nephropathy especially MN and treated according to MN will get good therapeutic effect.

Keywords: Case report; Leukocyte chemotactic factor 2 amyloidosis (ALECT2); Membranous nephropathy (MN); Monotypic; Phospholipase A2 receptor (PLA2R).

Fig. 1

Light and Electron micrographs of biopsy kidney specimen from the patient. A Amyloids deposit in the interstitium. Periodic Acid-Schiff stain × 400, B Amyloids deposit in afferent arteriole and some mesangial area. Erythrophilic complex deposits on the epithelial side. Masson stain × 400, C, D Congo red-positive amyloid deposits, with apple-green birefringence, seen in the mesangial area and interstitium. C Congo red × 400, D Congo red under polarized light microscopy × 400, E Subepithelial electron-dense deposits with intervening “spikes” and Amyloid fibrils found in subendothelial spaces. EM × 30,000, F Amyloid fibrils found in interstitial area. EM × 7500/ × 90000

Fig. 2

Immunofluorescenct/immunohistochemistry micrographs of the biopsy kidney. Diffuse granular deposition of IgG, κ light chain and anti-PLA2R antibody along the glomerular basement membrane (GBM). λ light chain deposition was seen weakly in interstitium and not seen along the GBM. LECT2 was stained predominantly on amyloid deposits by immunohistochemistry. IgG × 400, PLA2R1 × 400, Light chain κ × 400, Light chains λ × 400, LECT2 × 200