Acute tubulointerstitial nephritis with severe renal impairment associated with multisystem IgG4-related disease

Abstract The IgG4-related disease has a wide clinical spectrum where multiple organs can be affected, and the diagnosis depends on typical histopathological findings and an elevated IgG4 expression in plasma cells in the affected tissue. We describe the clinical presentation and evolution of a patient with acute tubulointerstitial nephritis, severe kidney failure and systemic manifestations such as lymphadenomegaly and chronic pancreatitis. The diagnosis was confirmed by the clinical picture and kidney and lymph node histopathology, in which immunohistochemistry of the lymphoid tissue showed policlonality and increased expression of IgG4, with a IgG4/total IgG ratio > 80%. The patient was treated with prednisone at a dose of 60 mg/day, followed by mycophenolate mofetil, and showed clinical and renal function improvement at 6 months of follow-up. The high index of suspicion of IgG4-related disease with multisystem involvement and the early treatment of this condition are essential to improve the prognosis of affected patients.

摘要 IgG4相关性疾病（IgG4-related disease）临床谱广泛，可累及多个器官，其诊断依赖典型的组织病理学表现及受累组织中浆细胞IgG4表达升高。本文报告1例合并急性肾小管间质性肾炎、重度肾衰竭及淋巴结肿大、慢性胰腺炎等全身表现的患者的临床特征与病程转归。该患者的诊断通过临床表现、肾脏及淋巴结组织病理学检查得以确诊：淋巴组织免疫组织化学检测显示多克隆性且IgG4表达升高，IgG4/总Ig比值＞80%。患者予以泼尼松60mg/日口服治疗，后续换用吗替麦考酚酯，随访6个月时临床症状及肾功能均得到改善。对多系统受累的IgG4相关性疾病保持高度怀疑并尽早开展治疗，对改善患者预后至关重要。