PMC5399208_01
Gradual progression of tubulointerstitial nephritis. (A) Chronic tubulointerstitial nephritis (TIN) and collapse of glomeruli; Periodic acid-Schiff stain (x100). (B) Secondary perihilar glomerulosclerosis; Periodic acid-Schiff stain (x400). (C, D) Collapsing glomeruli on electron microscopy (x4,000, x1,500). (E) Widespread infiltration of many lymphocytes and plasma cells into the interstitium; Hematoxylin and Eosin staining (x400). (F) The tubular basement membranes (TBMs) were thickened, and the epithelium was flattened with complete loss of the brush border (obsolete TIN, upper half). Lymphocytes infiltrated into the tubules, but the structures of the tubules were intact (active TIN, lower half); Periodic acid-Schiff stain (x400).
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Fifteen glomeruli had normal features, 23 showed complete sclerosis, and 2 showed segmental sclerosis (Fig. 1A). One glomerulus showed perihilar segmental sclerosis (Fig. 1B). Foot process fusions were not obvious (Fig. 1C and D). No eosinophilic infiltration was found (Fig. 1E). The tubular structures were intact, and there was scattered mild lymphocytic infiltration of the tubules (Fig. 1F, lower side). In some areas, a collection of atrophic tubules with thickened basement membranes and flattened epithelia with complete loss of the brush border were found (Fig. 1F, upper half).
Widespread calcification of the distal tubules. (A) A number of crystals broadly deposited in the distal tubules were stained basophilic by Hematoxylin and Eosin staining (x400). The black arrows indicate the location of the crystals. (B) The crystals were stained black by von Kossa stain (x400). (C, D) The crystals in the distal tubules had a high density on electron microscopy (x1,500, x1,200).
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The crystals, which were stained basophilic by Hematoxylin and Eosin staining (Fig. 2A) and black by von Kossa stain, included calcium crystals (Fig. 2B). On electron microscopy, the crystals in the distal tubules had a high density (Fig. 2C and D).