Anca-associated crescentic glomerulonephritis in a child with isolated renal involvement

ABSTRACT Pauci-immune glomerulonephritis (GN) is more common in elderly people compared to children and the etiology is not completely understood yet. Antineutrophil cytoplasmic antibody (ANCA) positivity occurs in 80% of the patients. We report a case of a 7-year-old girl who presented with malaise and mildly elevated creatinine diagnosed as ANCA-associated pauci-immune crescentic glomerulonephritis with crescents in 20 of 25 glomeruli (80%). Of these 20 crescents, 12 were cellular, 4 fibrocellular, and 4 globally sclerotic. She did not have purpura, arthritis, or systemic symptoms and she responded well to initial immunosuppressive treatment despite relatively severe histopathology. The patient was given three pulses of intravenous methylprednisolone (30 mg/kg on alternate days) initially and continued with cyclophosphamide (CYC; 2 mg/kg per day) orally for 3 months with prednisone (1 mg/kg per day). In one month, remission was achieved with normal serum creatinine and prednisone was gradually tapered. The case of this child with a relatively rare pediatric disease emphasizes the importance of early and aggressive immunosuppressive treatment in patients with renal-limited ANCA-associated pauci-immune crescentic GN even if with a mild clinical presentation. As in our patient, clinical and laboratory findings might not always exactly reflect the severity of renal histopathology and thus kidney biopsy is mandatory in such children to guide the clinical management and predict prognosis.

摘要 寡免疫复合物性肾小球肾炎（pauci-immune glomerulonephritis, GN）在老年人群中的发病率高于儿童，其病因尚未完全阐明。80%的患者可检测到抗中性粒细胞胞浆抗体（antineutrophil cytoplasmic antibody, ANCA）阳性。本文报告1例7岁女童病例：该患儿以全身乏力、血清肌酐轻度升高为首发表现，确诊为ANCA相关性寡免疫复合物性新月体性肾小球肾炎，肾活检提示25个肾小球中20个（占比80%）存在新月体形成，其中12个为细胞性新月体、4个为纤维细胞性新月体、4个为全球性硬化性新月体。该患儿无紫癜、关节炎或全身系统性症状，尽管肾脏组织病理学表现相对严重，但初始免疫抑制治疗应答良好。患者初始接受3次静脉甲泼尼龙冲击治疗（隔日30mg/kg），随后予以口服环磷酰胺（cyclophosphamide, CYC；每日2mg/kg）联合泼尼松（每日1mg/kg）治疗3个月。治疗1个月后患者达到临床缓解，血清肌酐恢复正常，随后逐渐递减泼尼松剂量。本病例为一例相对罕见的儿童寡免疫复合物性肾小球肾炎病例，强调了即使临床表型较轻，肾局限性ANCA相关性寡免疫复合物性新月体性GN患者也需尽早给予积极的免疫抑制治疗。与本例患者类似，临床及实验室检查结果有时并不能完全反映肾脏组织病理学的严重程度，因此此类患儿需行肾活检以指导临床诊疗并预测预后。