Fig. 1
Light microscopy findings of the renal biopsy specimen. a Interstitium showing extensive plasma cell infiltration, partial accumulation of eosinophils, and lymphocytes (haematoxylin-eosin staining, original magnification × 100). b Interstitium showing plasma cell infiltration (arrow) and storiform fibrosis with tubule atrophy (periodic acid-Schiff staining, original magnification × 400). Marked increase in IgG4-positive plasma cells was seen in the infiltrate (immunofluorescence staining for IgG4, original magnification × 400). c The glomeruli showing spike formation and bubbling on the glomerular capillary walls (periodic acid methenamine silver-Masson trichrome, original magnification × 1000)