摘要目的 对不典型膜性肾病(AMN)的病理特点进行分析,并评估其诊断价值.方法 选取2011年至2017年首都医科大学附属北京安贞医院肾内科经肾穿刺病理检查诊断为AMN的患者91例.依据肾组织M型磷脂酶A2受体(PLA2R)和1型血小板反应蛋白7a域(THSD7A)免疫组化染色结果 ,将其分为AMN组(PLA2R和THSD7A均阴性,25例)和特发性膜性肾病(IMN)组(PLA2R或THSD7A阳性,66例).比较两组患者的免疫荧光、光镜和电镜检查结果,筛选出差异有统计学意义的指标,采用四格表评估其诊断AMN的价值.结果免疫荧光结果中AMN组IgG同时沉积于毛细血管壁和系膜区、IgG4阴性而其他IgG亚类和补体C1q阳性的比例均高于IMN组(分别56.0％比12.1％,44.0％比0,均P<0.05),其诊断AMN的特异度分别为87.9％、100.0％.而IgG伴IgA和(或)IgM阳性、以IgG4为主伴其他IgG亚类和补体C1q阳性的比例两组间差异均无统计学意义(均P>0.05).光镜检查中AMN组基底膜"假双轨征"、上皮下伴其他部位的嗜复红蛋白沉积的比例均高于IMN组(分别36.0％比0,44.0％比1.5％,均P<0.05),其诊断AMN的特异度分别为100.0％、98.5％.而两组肾小球系膜细胞增生积分差异无统计学意义(P>0.05).电镜结果中AMN组内皮下电子致密物沉积的比例高于IMN组(36.0％比1.5％,P<0.05),其诊断AMN的特异度为98.5％.结论 在未进行PLA2R和THSD7A相关检查时,IgG同时沉积于毛细血管壁和系膜区、IgG4阴性而其他IgG亚类和补体C1q阳性、基底膜"假双轨征"、上皮下伴其他部位的嗜复红蛋白沉积、上皮下伴内皮下电子致密物沉积均有助于诊断AMN.

abstractsObjective To evaluate the diagnostic value of pathological features of atypical membranous nephropathy (AMN). Methods Ninety - one patients with AMN diagnosed by renal biopsy during 2011 and 2017 were enrolled in this study. On the basis of M - type phospholipase A2 receptor (PLA2R) and thrombospondin type - 1 domain - containing 7A protein (THSD7A) by immunohistochemistry, patients were divided into AMN group (25 cases without PLA2R and THSD7A) and idiopathic membranous nephropathy (IMN) group (66 cases with positive PLA2R or THSD7A). The results of immunofluorescence (IF), light microscopy (LM) and electron microscopy (EM) of these two groups were compared, and the parameters with statistical difference were screened out in order to assess their value in the diagnosis of AMN in fourfold table. Results IF results showed that in AMN group the proportions of IgG deposition on capillary wall and mesangial area as well as positive otherIgG subclasses and complement C1q but negative IgG4 were significantly higher than those in IMN group (respectively, 56.0％ vs 12.1％ , 44.0％ vs 0, both P＜0.05). Their diagnostic specificities for AMN were 87.9％ and 100.0％, respectively. However, the positive rates of IgG accompanied with IgA and/or IgM, predominant IgG4 with other IgG subclasses and complement C1q in two groups were not significantly different (all P＞0.05). LM results showed that the proportions of false double track sign on basement membrane and fuchsinophilic proteins under epithelium, endothelium, basement membrane and mesangial region in AMN group were significantly higher than those in IMN group (respectively, 36.0％ vs 0, 44.0％ vs 1.5％, both P＜0.05). Their diagnostic specificities for AMN were 100.0％ and 98.5％ , respectively. However, the scores of mesangial cell proliferation of these two groups showed no significantly difference (P＞0.05). EM results showed that the rate of endothelial electron dense deposits in AMN group was significantly higher than that in IMN group (36.0％ vs 1.5％, P＜0.05), and its diagnostic specificity for AMN was 98.5％. Conclusions IgG deposition on both capillary wall and mesangial area, positive other IgG subclasses and C1q with negative IgG4, false -double contour sign, multi - site fuchsinophilic deposits and endothelial electron dense deposits may help for the AMN diagnosis in the absence of PLA2R and THSD7A related data.