Nat. Rev. Nephrol. doi:10.1038/nrneph.2017.10 Figure 2 Histopathological changes in nephron-associated crystal nephropathies (type 2) Figure 2 | Histopathological changes in nephron-associated crystal nephropathies (type 2). a | In a patient with acute kidney injury (AKI) (serum creatinine levels of 4 mg/ml [353.6 μmol/l]) and increased serum bilirubin and liver function tests, tubular epithelial cells were swollen, stained yellow to brown (positive for bile with Faucet stain) and had focal tubular brown casts (haematoxylin and eosin staining). b | In a patient with metabolic acidosis, ethylene glycol intoxication, serum creatinine levels of 2.41 mg/ml (213.0 μmol/l), and an estimated glomerular filtration rate of 28 ml/min/1.73 m2, tubular cells stained with haematoxylin and eosin had numerous colourless fan-shaped calcium oxalate tubular crystals. The crystals polarize light and some of them are polychromatic (insert). c | Rhabdomyolysis-induced tubular casts (stained in brown with an anti-myoglobin antibody) in a young man with a history of strenuous exercise and severe AKI requiring dialysis. d | A 70-year-old man with chronic kidney disease and a history of monoclonal gammopathy of undetermined significance had needle-shaped paraprotein intracytoplasmic crystals (arrow) in the proximal tubules. e | Numerous pale rhomboid tubular crystals were present in a renal biopsy sample from a 60-year-old man with refractory multiple myeloma and κ light chain restrictions (haematoxylin and eosin staining). f | A 62-year-old woman with AKI and clinical suspicion of multiple myeloma had a proximal tubulopathy, as shown by an intense cytoplasmic κ light chain staining. g,h | In a 55-year-old man with long-standing hypertension, nephrotic range proteinuria, slowly progressive renal function impairment (serum creatinine levels of 2.4 mg/ml [212.2 μmol/l]), crystal podocytopathy and crystal cast nephropathy, podocytes (panel g) and tubules (panel h) are filled with rectangular or rhomboid crystals (arrows), as seen by transmission electron miscropscopy. The insert in g pictures the rhomboid crystals inside the podocyte at high magnification. i | A patient with immunotactoid glomerulopathy had thick tubular deposits in the glomeruli (electron-dense material seen by transmission electron miscropscopy), and expanded glomerular mesangium and thickened capillary loops (not shown here); congo red stain and immunofluorescent staining of immunoglobulins and complement were negative. Images courtesy of Helen Liapis, Arkana Laboratories, USA. Mulay, S. R. & Anders, H.-J. (2017) Crystal nephropathies: mechanisms of crystal-induced kidney injury Nat. Rev. Nephrol. doi:10.1038/nrneph.2017.10