目的：探讨IgG4相关性腹膜后纤维化（retroperitoneal fibrosis, RPF）的临床特征、治疗及预后。方法：收集2008年2月至2014年10月期间北京大学人民医院诊断的RPF病例32例，分析其中IgG4相关性RPF病例的临床资料，并结合国内外相关文献，总结该病的临床表现、实验室检查和影像学检查特点、治疗方法及预后。结果：纳入IgG4相关性RPF共5例，均为男性，平均年龄62.2岁（55~67岁），患者表现为腹痛、腰痛、体重减轻等症状，2例患者合并自身免疫性胰腺炎（antoimmune pancreatitis, AIP），3例患者（3/5）肾功能减退，4例患者（4/4）动态红细胞沉降率（erythrocyte sedimentation rate，ESR）升高，3例患者（3/4）C-反应蛋白（C-reactive protein，CRP）升高，3例患者（3/4）血IgG升高，4例患者（4/4）血IgG4升高。计算机断层扫描（computed tomography, CT）均提示腹膜后软组织影包绕腹主动脉、髂动脉，甚至输尿管和下腔静脉。1例患者行腹膜后组织病理检查，提示IgG4阳性浆细胞与IgG阳性浆细胞比例>40%，且IgG4阳性浆细胞>10个/高倍视野。1例接受单纯手术治疗，1例接受单纯药物治疗，3例接受手术和药物联合治疗，4例获得随访的患者中，预后均较好。结论：部分RPF可能是IgG4相关性疾病的一种临床表现，即IgG4相关性RPF，其病因不明，血清IgG4浓度升高（≥1.35 g/L），组织病理学显示有明显淋巴细胞和IgG阳性浆细胞浸润伴纤维化，首选糖皮质激素治疗，预后较好。

Objective：To explore the clinical characteristics, treatment and prognosis of IgG4-related retroperitoneal fibrosis (RPF). Methods: All the patients diagnosed as RPF in Peking University People’s Hospital between February 2008 and October 2014 were included. Among them, 5 patients were identified as IgG4 related RPF. We analyzed their medical records and summarized the clinical, laboratory, and imaging features of IgG4 related RPF, which had taken the recent literature into account. Results: All the 5 patients were male, with the average age 62.2 years (55-67 years). They mainly complained of abdominal pain, flank pain and weight loss, two of whom had concurrent antoimmune pancreatitis. Renal insufficiency was present in 3 patients (3/5). Four patients (4/4) showed increased erythrocyte sedimentation rate (ESR), while 3 patients (3/4) had higher serum C-reactive protein (CRP) and IgG. In addition, 4 patients (4/4) had significantly elevated serum IgG4 level. On computed tomography (CT) imaging, 5 patients showed retroperitoneal mass which surrounded the abdominal aorta and the iliac arteries, and even enveloped the ureters and the inferior vena cava. Only one patient received tissue pathological examination, which indicated the numbers of IgG4-positive plasma cells per high power field >10 and a ratio of IgG4-positive cells to all IgGbearing cells >40%. One patient received simple surgical intervention, and 1 patient received medical treatment alone, while the remaining 3 patients received combined treatment of surgery and medications. Follow-up was available for the 4 patients, all of whom had good prognosis. Conclusion: Part of RPF was actually IgG4-related, which was also nominated as IgG4 related RPF. It was a rare disease with unknown etiology, characterized by the elevated serum IgG4 concentration (≥1.35 g/L), with marked tissue infiltration by lymphocytes and IgG4-positive plasma cells with fibrosis, in addition to the presence of retroperitoneal mass. Glucocorticoids were the first-line therapy and IgG4 related RPF had a favourable prognosis.