Fig. 1

Pathology specimen of the graft biopsy of a patient who received a kidney transplant 19 month prior and now had proteinuria (200X magnification unless otherwise specified). a Hematoxylin and eosin: Endocapillary proliferation is seen in the glomeruli. b Hematoxylin and eosin: A peritubular capillary involved by numerous lymphocytes and arrow showing ptc2. c Hematoxylin and eosin: brown granular pigments of 2 μm on average are seen. d Masson-Trichrome: The granules are darker than the surrounding cytoplasm in the tubular cells. e Periodic-acid Schiff: Tubular epithelium with light brown to magenta granules. f Schmorl reaction: The blue coloration of the granules is highlighted. g Fontana: The black coloration of the granules is highlighted. h Prussian blue: the granules are negative for iron staining. i Jone’s silver: the granules are negative for silver staining. j Immunofluorescence (400x magnification): The granules show autofluorescence, exhibited by molecules with fluorophore-like property upon excitation. k Electron microscopy (700x magnification): Tubular cell with intracytoplasmic inclusions, compatible with lipofuscin. They have a lamellar arrangement and a granular matrix (arrow), usually surrounded by mitochondria (arrowhead)