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. 2015 Sep 15;27(5):1555–1565. doi: 10.1681/ASN.2015020185

Figure 1.

Figure 1.

Light microscopic findings in crystalline LCPT. (A) Proximal tubular cells are engorged by abundant fuchsinophilic small crystalline inclusions that distort the nuclei and obscure the apical cell membrane, filling the tubular lumen. There is adjacent mild interstitial fibrosis and inflammation without tubulitis (trichrome, ×600). (B) Proximal tubular cells are distorted by elongated highly fuchsinophilic needle-shaped inclusions. Some of the tubular cells are flattened, and others display shedding of cytoplasmic fragments into the lumen. An atypical hard cast is present in a distal tubule (trichrome, ×600). (C) Distinct crystals of varying size and number are brightly trichrome-red and exhibit a variety of geometric shapes from rectangular to rhomboidal (trichrome, ×400). (D) The proximal tubular cells contain abundant large, elongated, optically clear, or weakly eosinophilic crystals that distort the cell architecture (hematoxylin and eosin stain, ×600). (E) There is variable individual proximal tubular cell vacuolation containing finely granular punctate eosinophilic inclusions that could be resolved as crystalline only at the ultrastructural level. Some proximal tubular nuclei appear to be undergoing apoptosis. (hematoxylin and eosin stain, ×600). (F) The same biopsy as Figure 1E shown with trichrome stain highlights the granular trichrome-red inclusions and vacuolated appearance of individual proximal tubular cells side by side with more normal appearing cells (trichrome, ×600). (G) Crystals are shed from the apical surfaces of injured proximal tubular cells into the tubular lumen, forming atypical loose casts with sharp edges. No giant cell reaction is seen. The adjacent interstitium is expanded by fibrosis and chronic inflammation (trichrome ×600). (H) A glomerulus with abundant crystalline inclusions within the cytoplasm of engorged podocytes (trichrome, ×600). (I) An example of crystal-storing histiocytosis with needle-shaped fuchsinophilic crystals within the cytoplasm of interstitial histiocytes. Similar crystals are present in the proximal tubular cells of an adjacent tubule at bottom left (trichrome, ×600).