Primary membranous nephropathy combined with ALECT-2 renal amyloidosis：a case report

Abstract

Abstract Background Primary membranous nephropathy (PMN) is an autoimmune kidney disease and the leading cause of nephrotic syndrome in adults. It is characterized by the accumulation of immune deposits leading to glomerular basement membrane dysfunction caused by the deposition of subepithelial immune complexes. Amyloidosis is a rare group of diseases characterized by abnormal protein folding and extracellular deposition of insoluble protofibrils. It can be limited to one organ system or affect the entire body. In systemic amyloidosis, the kidney is the most commonly affected organ, often leading to renal failure and nephrotic syndrome. PMN combined with renal amyloidosis without secondary factors is rare. In this study, we report a case of PMN combined with amyloid nephropathy with only interstitial immunoglobulin light chain deposits. Case reportThis article reports a case of membranous nephropathy associated with ALECT-2 amyloidosis with nephrotic syndrome. A 62-year-old woman with the nephrotic syndrome had positive antiphospholipase A2 receptor (PLA2R) antibodies and a renal biopsy suggesting stage II membranous nephropathy, but a few focal deposits of faintly stained material were seen in the interstitium with positive expression of PAS and Congo red. It is rare for membranous nephropathy to be complicated by ALECT-2 protein deposition, and even rarer for it to be deposited only in the interstitium. Mass spectrometry can be used clinically as an aid to diagnosis and treatment is based on the treatment of primary glomerular disease with supportive therapy for ALECT-2 renal amyloidosis. Conclusion The combination of PMN and amyloidosis is rare and attention should be paid to the subtype of the disease and the exclusion of secondary factors. A thorough clinical and pathological examination will help in the classification and staging of the disease. Detection of serum anti-PLA2R antibodies and glomerular PLA2R antigen is helpful in the diagnosis of PMN. ALECT-2 amyloidosis has a relatively benign progression and renal biopsy is helpful in the diagnosis. For amyloidosis with unknown typing, further typing can be refined with genetic testing or mass spectrometry. We look forward to finding novel therapeutic options that can target both PMN and ALECT-2 amyloid nephropathy in the future.