Fig. 1

Renal biopsy. a Light microscopy of the renal biopsy (periodic acid–Schiff stain) revealed normal glomerulus with formation of interstitial granulomas indicated by arrow heads. Granulomas were composed of lymphocytes, plasma cells, macrophages, epithelioid cells, and multinucleated giant cells. Bar = 100 μm. b Magnified picture of marked area in a, revealing a focal distribution of mononuclear cell infiltrates in the interstitium, associated with focal tubular atrophy, with tubulointerstitial edema as indicated by black arrow head, and with mild tubulitis with intraepithelial lymphocytes, as indicated by white arrow heads. The moderate diffuse interstitial inflammation is composed of lymphocytes and eosinophils. Bar = 50 μm