Fig. 3

Kidney biopsy slide specimen showing: a subcapsular and medullary ray fibrosis in 10% of the specimen, b mild mesangial expansion in the glomeruli, c focal but severe lymphocyte infiltration and tubulitis, d tubular epithelium injury with nuclear denudation or tubular dilatation, and e interstitial monocyte infiltration and tubulitis mainly distributed in the medullary ray lesion [a, Masson trichrome, × 2; b, c, Periodic acid–Schiff, × 40 and × 20, respectively; d, Periodic acid–methenamine–silver, × 40; e, Tamm–Horsfall protein staining added on Periodic acid–Schiff, × 10]