Perirenal IgG4-related disease

A 73-year-old man presented with incidental left pleural effusion, which was diagnosed on the basis of a chest X-ray. Laboratory analyses showed microcytic anemia. Computed tomography revealed left pleural effusion and an infiltrative mass in the left retroperitoneum, involving the perirenal space with left kidney encasement (Figure 1a ). Diagnostic thoracentesis showed no evidence of microorganisms or presence of malignant cells. Subsequent computed tomography–guided biopsy of the left perirenal infiltrative mass revealed IgG4-related disease (Figure 2). Oral hydroxychloroquine (200 mg twice a day) and prednisolone (5 mg per day, tapered to twice a week over 6 months) were administered. After 6 months of medical treatment, follow-up computed tomography (Figure 1b) showed no detectable residual lesions. Figure 2(a) Light microscopy demonstrates fibroinflammatory process with loose to dense infiltrate lymphoplasmacytic cells, fibroblasts, and a few eosinophils in a collagenized stroma. Hematoxylin and eosin staining was used (original magnification ×400). (b) IgG4-positive cells were infiltrated, up to 15/high-power field. Immunostaining was used (original magnification ×400). To optimize viewing of this image, please see the online version of this article at www.kidney-international.org. View Large Image Figure Viewer Download Hi-res image