Rationale & Objective

Atypical anti-glomerular basement membrane (GBM) nephritis is characterized by a bright linear immunoglobulin staining along the GBM by immunofluorescence without a diffuse crescentic glomerulonephritis nor serum anti-GBM antibodies by conventional ELISA. We characterized a series of patients with atypical anti-GBM disease.

Study Design

Case series.

Setting & Participants

Patients were identified by the French Nephropathology Group as having atypical anti-GBM nephritis between 2003 and 2022.

Findings

Among 38 potential cases, 25 were included. 14 (56%) were female and 23 (92%) had hematuria. Median [interquartile range (IQR)] serum creatinine at diagnosis was 150 [102-203] μmol/L and median [IQR] urine protein to creatinine ratio was 2.4 [1.3-5.2] g/g. 9 (36%) patients had endocapillary proliferative glomerulonephritis (GN), 4 (16%) had mesangial proliferative GN, 4 (16%) had membranoproliferative GN, 2 (8%) had pure and focal crescentic GN, 1 (4%) had focal segmental glomerulosclerosis, and 5 had glomeruli that were unremarkable on histopathology. Nine patients (36%) had crescents, involving a median of 9% of glomeruli. Bright linear staining for IgG was seen in 22 cases (88%) and for IgA in 3 cases (12%). The nine patients (38%) who had a monotypic staining pattern tended to be older with less proteinuria and rarely had crescents. Kidney survival rate at one year was 83% and did not appear to be associated with the light chain restriction.

Limitations

Retrospective case series with a limited number of biopsies including electron microscopy.

Conclusions

Compared to typical anti-GBM disease, atypical anti-GBM nephritis frequently presents with endocapillary or mesangial proliferative glomerulonephritis pattern and appears to have slower disease progression. Further studies are needed to fully characterize its pathophysiology and associated clinical outcomes.

中文翻译：

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非典型抗肾小球基底膜肾炎：法国肾脏病理学小组的病例系列

理由和目标

非典型抗肾小球基底膜 (GBM) 肾炎的特征是通过免疫荧光法沿 GBM 出现明亮的线性免疫球蛋白染色，而通过常规 ELISA 检测，没有弥漫性新月体肾小球肾炎，也没有血清抗 GBM 抗体。我们对一系列患有非典型抗 GBM 疾病的患者进行了表征。

学习规划

案例系列。

背景及参与者

法国肾脏病理学小组在 2003 年至 2022 年间诊断出患有非典型抗 GBM 肾炎的患者。

发现

在 38 个潜在病例中，纳入了 25 个。14 名（56%）为女性，23 名（92%）有血尿。诊断时血清肌酐中位数[四分位距 (IQR)] 为 150 [102-203] μmol/L，尿蛋白与肌酐比中位数 [IQR] 为 2.4 [1.3-5.2] g/g。9 例 (36%) 患者患有毛细血管内增生性肾小球肾炎 (GN)，4 例 (16%) 患有系膜增生性 GN，4 例 (16%) 患有膜增生性 GN，2 例 (8%) 患有单纯性局灶性新月体 GN，1 例 (4%)患有局灶节段性肾小球硬化，5 名肾小球组织病理学未发现异常。9 名患者 (36%) 出现新月体，平均累及 9% 的肾小球。22 例 (88%) 可见 IgG 明亮线性染色，3 例 (12%) 可见 IgA 明亮线性染色。具有单一染色模式的 9 名患者 (38%) 往往年龄较大，蛋白尿较少，且很少出现新月体。一年的肾脏存活率为 83%，似乎与轻链限制无关。

局限性

回顾性病例系列，包括电子显微镜检查在内的有限数量的活检。

结论

与典型的抗 GBM 疾病相比，非典型抗 GBM 肾炎经常表现为毛细血管内或系膜增生性肾小球肾炎模式，并且疾病进展似乎较慢。需要进一步的研究来充分表征其病理生理学和相关的临床结果。