Yamaguchi Yuya, Tosaki Takeshi, Sasaki Takaya, Nakashima Daisuke, Honda Yu, Yokote Shinya, Tsuboi Nobuo, Yokoo Takashi
Department of Nephrology, Kawaguchi Municipal Medical Center, Saitama, Japan.
Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, 3-25-8 Nishi-Shimbashi, Minato-Ku, Tokyo, Japan.
CEN Case Rep. 2025 Aug 13. doi: 10.1007/s13730-025-01023-z.
Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease associated with inflammation implicated in the development of vasculitis, specifically microscopic polyangiitis (MPA). Herein, we report a case of MPA complicated by IPF. A woman in her 70s with a history of IPF treated with nintedanib presented with a serum creatinine level of 2.22 mg/dL, microscopic hematuria, and a serum myeloperoxidase-antineutrophil cytoplasmic antibodies (MPO-ANCA) titer level of 78.5 IU/mL. The initial renal biopsy revealed diffuse tubulointerstitial nephritis without glomerular crescent formation; therefore, prednisolone was initiated. However, the serum MPO-ANCA titer level increased to 91.1 IU/mL after tapering the prednisolone dose. A second renal biopsy revealed pauci-immune necrotizing glomerulonephritis with crescents, confirming MPA. Treatment was adjusted to include a resumed steroid regimen and combination therapy with rituximab and avacopan, resulting in stable kidney function. In conclusion, this case underscores the importance of monitoring serum ANCA titer levels as a surrogate marker for subclinical vasculitis in patients with IPF. The sequential occurrence of tubulointerstitial nephritis followed by crescentic glomerulonephritis suggests a potential progression pattern in MPA, warranting careful clinical and histopathological evaluations.
特发性肺纤维化（IPF）是一种慢性进行性肺部疾病，与血管炎（特别是显微镜下多血管炎，MPA）的发生发展相关的炎症有关。在此，我们报告一例MPA合并IPF的病例。一名70多岁有IPF病史且接受尼达尼布治疗的女性，血清肌酐水平为2.22mg/dL，出现镜下血尿，血清髓过氧化物酶抗中性粒细胞胞浆抗体（MPO-ANCA）滴度水平为78.5IU/mL。最初的肾活检显示弥漫性肾小管间质性肾炎，无肾小球新月体形成；因此，开始使用泼尼松龙治疗。然而，在逐渐减少泼尼松龙剂量后，血清MPO-ANCA滴度水平升至91.1IU/mL。第二次肾活检显示寡免疫坏死性新月体性肾小球肾炎，确诊为MPA。治疗调整为恢复类固醇治疗方案，并联合使用利妥昔单抗和阿伐库潘，肾功能得以稳定。总之，该病例强调了监测血清ANCA滴度水平作为IPF患者亚临床血管炎替代标志物的重要性。肾小管间质性肾炎随后出现新月体性肾小球肾炎的相继发生提示了MPA的一种潜在进展模式，需要仔细的临床和组织病理学评估。
