case_images: PMC11774644_01
case_images: Light microscopy appearance of erythrocyte casts within the renal cortex and medulla. Scattered intratubular erythrocyte casts are present in the renal medulla (A,B). Scattered granular epithelial cell casts are also present (black arrow in B). Erythrocyte casts are present also within the sampled cortex (C,D), in addition to occasional granular epithelial cell casts (black arrow in D). Many of the medullary erythrocyte casts show "ghost" erythrocytes (E,F) that may be falsely regarded as granular epithelial cell casts when examined at low power. A rare cortical tubule shows erythrocytes incorporated into the cytoplasm of tubular epithelial cells (G), providing evidence that this bleeding into tubules occurred prior to the biopsy procedure, and is not artifactual in nature [A,B (hematoxylin & eosin), original magnification, 40x; C-G (hematoxylin & eosin), original magnification, 100x].
case_images: fmed-11-1434497-g001.jpg
case_images: PMC11774644_01_fmed-11-1434497-g001.jpg
case_images: fig1
case_images: Skin biopsy was not obtained; however, a kidney biopsy (Figures 1, 2) was performed, with sampling of 21 glomeruli. Light microscopy revealed intratubular erythrocyte and granular epithelial cell casts within the cortex and the medulla. "Ghost" erythrocytes, which could be misinterpreted as granular casts at low magnification (Figures 1E,F), were present, along with evidence of pre-biopsy intratubular bleeding (Figure 1G).
case_images: Light microscopy appearance of glomeruli and interstitial inflammation. Although no definitive endocapillary hypercellularity is present within the sampled glomeruli, rare trafficking neutrophils are present in glomerular capillaries (black arrow in A), a finding that is commonly seen in ANCA-related glomerular disease. There also are adjacent intratubular erythrocyte casts (blue arrow in A), which raise suspicion for unsampled crescentic glomerular disease (A). Some areas of sampled cortex have mixed interstitial inflammation with mononuclear leukocytes, plasma cells, eosinophils, and rare neutrophils, without significant associated tubulitis, although there is evidence of acute tubular injury (B). A rare focus of vaguely granulomatous inflammation by histiocytes with admixed inflammatory cells is present within the cortical interstitium (C), which also raises suspicion for unsampled ANCA glomerulonephritis. Granulomatous interstitial inflammation is not an uncommon finding in cases of ANCA-associated kidney disease. Examination of sampled glomeruli reveals no definitive lesions of fibrinoid necrosis or crescent formation but demonstrates mild mesangial hypercellularity and sclerosis, with associated thickening of glomerular capillary walls, consistent with early diabetic glomerular disease (D,E) [A,B (hematoxylin & eosin), original magnification, 40x; C (Jones methenamine silver), original magnification, 40x; D (periodic acid-Schiff), original magnification, 100x; E (Masson trichrome), original magnification, 100x].
case_images: fmed-11-1434497-g002.jpg
case_images: PMC11774644_01_fmed-11-1434497-g002.jpg
case_images: fig2
case_images: Skin biopsy was not obtained; however, a kidney biopsy (Figures 1, 2) was performed, with sampling of 21 glomeruli. Neutrophils were present in glomerular capillaries (Figure 2A), suggesting unsampled crescentic disease, though no definitive lesions of endocapillary hypercellularity were seen. Mixed interstitial inflammation consisted of mononuclear leukocytes, plasma cells, eosinophils, and rare neutrophils, with focal granulomatous inflammation (Figure 2C). Although there were no overt signs of fibrinoid necrosis or crescent formation, early diabetic glomerular changes, including mesangial hypercellularity and capillary wall thickening, were noted (Figures 2D,E).
case_images: PMC11774644_02