Rapidly Progressive Kidney Failure Associated with Perirenal Capsular Lesion Due to IgG4-Related Disease.

A 71-year-old Japanese man with progressive kidney failure was referred to our hospital. Laboratory tests showed elevated IgG4 levels. Contrast-enhanced computed tomography (CT) revealed soft tissue surrounding the left kidney and right atrophic kidney. A histopathological examination revealed inflammation and fibrosis with rich IgG4-positive cells in the thickened kidney capsule, but not in the kidney parenchyma. Poor enhancement in the left kidney on contrast-enhanced CT and wrinkling of glomerular capillaries in pathological tissues were also observed. These findings indicated IgG4-related perirenal lesions leading to low renal perfusion and kidney failure. The perirenal lesions and kidney failure were improved by corticosteroid therapy.