Staphylococcus Infection-Associated GN - Spectrum of IgA Staining and Prevalence of ANCA in a Single-Center Cohort
Staphylococcus Infection-Associated GN - Spectrum of IgA Staining and Prevalence of ANCA in a Single-Center Cohort
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DOI：
10.2215/cjn.05070516
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发表时间：
2017-01-01
影响因子：
9.8
通讯作者：
Nadasdy, Tibor
中科院分区：
文献类型：
--
作者：
Satoskar, Anjali A.;Suleiman, Sarah;Nadasdy, Tibor
背景和目的葡萄球菌感染相关GN （SAGN）是一种公认的疾病实体，特别是因为肾活检中经常出现iga显性肾小球免疫球蛋白染色。活检特征可能类似于其他两种疾病实体，原发性IgA肾病和过敏性紫癜性肾炎，这是一个诊断缺陷。这是临床相关的，因为治疗方法的关键差异。一些患者肾小球IgA（和C3）染色程度的变化、电子致密免疫型沉积的程度以及ANCA血清学阳性，使SAGN的诊断进一步复杂化。我们对78例经培养证实的SAGN活检的单中心队列进行了彻底的组织病理学检查，以评估IgA染色谱、ANCA血清学的患病率、上皮下“驼峰”的患病率和其他组织学特征，以区分原发性IgA肾病。结果78例SAGN活检中，25%为微量，19%为轻度，44%为中度，12%为强烈。C3通常为中度至重度，但在14%的活检中可见。13%的患者同时出现IgA、IgG和C3（缺乏免疫模式）。35%的SAGN活检中出现新月。在41例接受ANCA检测的患者中，9例（22%）呈阳性，包括心内膜炎和其他感染患者。只有31%的SAGN活检发现了上皮下肿块。结论与链球菌感染后的GN相比，SAGN活检在IgA免疫荧光染色上表现出明显的变异性，且上皮下隆起的频率较低。偶有ANCA阳性出现在SAGN病例中，甚至在心内膜炎以外的感染中也是如此。因此，活检诊断可能是困难的，特别是当感染的临床症状是微妙的。病理学家和肾科医生都应该意识到这些诊断缺陷。
Background and objectives Staphylococcus infection associated GN (SAGN) is a well recognized disease entity, particularly because of the frequent IgA-dorninant glomerular immunoglobulin staining on kidney biopsy. Biopsy features can resemble two other disease entities primary IgA nephropathy and Henoch-Schonleinpurpura nephritis - posing a diagnostic pitfall. This is clinically relevant because of the crucial difference in the therapeutic approach. The diagnosis of SAGN is further complicated by the variability in the degree of glomerular IgA (and C3) staining, the extent of electron dense immune-type deposits, and positive ANCA serology in some patients.Design, setting, participants, & measurements We performed a thorough histopathologic review of our single center cohort of 78 culture-proven SAGN biopsies to assess the spectrum of IgA staining, prevalence of ANCA serology, prevalence of subepithelial "humps," and other histologic features to distinguish from primary IgA nephropathy.Results Among the 78 SAGN biopsies, IgA staining was trace in 25%, mild in 19%, moderate in 44%, and strong in 12% of the cases. C3 was frequently moderate-to-strong but was trace in 14% of the biopsies. Concomitantly trace IgA, IgG, and C3 (pauci-immune pattern) was seen in 13%. Crescents were present in 35% of the SAGN biopsies. Out of 41 patients tested for ANCA, nine (22%) were positive, including patients with endocarditis and other infections. Subepithelial humps were identified in only 31% of the SAGN biopsies.Conclusions SAGN biopsies show marked variability in IgA immunofluorescence staining and low frequency of subepithelial humps compared with poststreptococcal GN. Occasional ANCA positivity is present in cases of SAGN, even in infections other than endocarditis. Therefore, biopsy diagnosis can be difficult particularly when clinical symptoms of infection are subtle. Both the pathologist and the nephrologist should be aware of these diagnostic pitfalls.