Fig. 2

Thrombotic microangiopathy in arterioles of resection specimen (a, b) and prior colonic mucosal biopsies (c, d). a Arterioles in muscularis propria with subendothelial fibrin. b Submucosal arterioles showing marked subendothelial edema with formation of concentric layers of new basement membrane material. c Capillaries/arterioles of deep lamina propria and superficial submucosa with intraluminal fibrin thrombi (arrows). Arteriole with subendothelial edema and new subendothelial basement membrane layer (arrowhead). d Superficial submucosal arteriole with subendothelial fibrin (arrow) and perivascular hemorrhage. (hematoxylin and eosin, original magnification ×400 for a–d)