A low-power view demonstrates widespread proximal tubular degenerative changes and interstitial edema. (a) A glomerulus appears unremarkable (hematoxylin and eosin, original magnification ×200). (b) At higher magnification, many proximal tubular cells are distended by numerous small intracytoplasmic PAS+ granules (arrow; periodic acid–Schiff, original magnification ×400). (c) Immunohistochemial staining for lysozyme shows intense granular reactivity in the distribution of proximal tubular cell cytoplasm (immunoperoxidase, original magnification ×100). (d) No significant staining is seen in a paired negative control obtained from an allograft postreperfusion biopsy (immunoperoxidase, original magnification ×100). (e) On ultrastructural evaluation, proximal tubular cells contain abundant membrane-bound vacuoles (arrow; original magnification ×8000). (f) On closer inspection, the vacuoles in proximal tubules contain clumped, degenerating organellar debris, consistent with autophagolysosomes (arrow; original magnification ×25,000). (g) In rare cells, the autophagolysomes appear to form larger, membrane-bound aggregates (arrow; original magnification ×6,000), corresponding to the (h) scattered large round eosinophilic inclusions seen in a minority of cells (arrow; hematoxylin and eosin, original magnification ×600).