IgG4-Related Kidney Disease with Retroperitoneal Fibrosis in a Patient with Diabetes Mellitus

Abstract

A 74-year-old man with type 2 diabetes mellitus, in whom persistent proteinuria and renal dysfunction had been noted for several years, developed a rapid increase in his serum creatinine concentration and was referred to our hospital because of concern about a potential exacerbation of diabetic nephropathy. Laboratory findings revealed high levels of serum IgG and IgG4. Computed tomography examination showed right hydronephrosis with retroperitoneal fibrosis. Although the hydronephrosis resolved with ureteral stent placement, the serum creatinine level further increased and renal biopsy was performed. Renal histology revealed tubulointerstitial nephritis with an abundant IgG4-positive plasma cell infiltrate and marked fibrosis, compatible with IgG4-related kidney disease (IgG4-RKD). The patient was treated with glucocorticoids and his serum creatinine level decreased to 1.5 mg/dL. This experience suggests that IgG4-RKD should be considered in cases of chronic kidney disease in which the renal dysfunction progresses rapidly without apparent cause, and that IgG4-RKD may be accompanied by retroperitoneal fibrosis in IgG4-related disease.