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Abstract：
Membranous nephropathy is an immune disease that commonly presents as nephrotic syndrome. The understanding of the pathogenesis of membranous nephropathy has rapidly evolved over the past few years due to the discovery of newer antigens. Exostosin 1 and exostosin 2 are antigens discovered in 2019 and found to be specific for membranous nephropathy secondary to autoimmune disease and are usually not seen in M-type phospholipase A2-associated membranous nephropathy. However, fewer clinical and pathological details of exostosin 1 and 2 related nephropathies are known, owing to the novelty of the antigen. Here we report a 24-year-old female who presented with nephrotic range proteinuria. Initial blood investigations revealed a doubtful autoimmune disease background. A subsequent renal biopsy revealed membranous nephropathy with both PLA2r and exostosin 1 positivity, which posed challenges in both diagnosis and treatment. Immunoglobulin G staining and electron microscopy were performed to differentiate if it was a PLA2r-associated or a exostosin 1/ exostosin 2-related membranous nephropathy. Electron microscopy revealed subepithelial deposits and immunoglobulin G stained for immunoglobulin G4, signifying possible PLA2r-associated membranous nephropathy with exostosin deposits. The patient was treated with rituximab and had a good treatment response. Only one similar case has been reported with both PLA2R and exostosin positivity. The pathophysiologic mechanism of this unique association is still unclear.
摘要：
膜性肾病是一种免疫性疾病，通常表现为肾病综合征。在过去的几年中，由于发现了新的抗原，对膜性肾病发病机理的理解迅速发展。外泌素1和外泌素2是2019年发现的抗原，发现对继发于自身免疫性疾病的膜性肾病具有特异性，通常在M型磷脂酶A2相关的膜性肾病中看不到。然而,已知外生骨素1和2相关肾病的临床和病理细节较少，由于抗原的新颖性。在这里，我们报告了一名24岁的女性，她患有肾病性蛋白尿。最初的血液检查显示了可疑的自身免疫性疾病背景。随后的肾活检显示膜性肾病，PLA2r和外生骨素1阳性，这在诊断和治疗方面都带来了挑战。进行了免疫球蛋白G染色和电子显微镜检查，以区分它是PLA2r相关的还是外生骨素1/外生骨素2相关的膜性肾病。电子显微镜检查显示上皮下沉积物和免疫球蛋白G对免疫球蛋白G4染色，表明可能与PLA2r相关的膜性肾病伴外植体蛋白沉积物。患者接受了利妥昔单抗治疗，治疗反应良好。仅报道了一例PLA2R和外生骨素阳性的类似病例。这种独特关联的病理生理机制尚不清楚。
