In the setting of severe atheromatous disease, in a patient with ESKD, ischemic colitis should be sought as the most likely etiology for colitis. Further surgical resection confirmed ischemic colitis. 

Macroscopy: Labeled "Right colon and terminal ileum".  A length of colon comprising cecum and ascending colon 185 x 55 mm, and small bowel 682 x 35mm. The appendix is absent.  There is attached mesocolic fat up to 55 mm in maximum dimension.  The serosal surface is pale and fibrotic over the cecum, bearing fibrinopurulent exudate, and the serosa covering the small bowel is pale and fibrotic, bearing patchy hemorrhage in the midportion. The mucosa of the small bowel is alternately diffusely dark brown-black with a thin wall, <1 mm in areas and patchily brown/ulcerated.  There is a 60mm length of normal tan mucosa with preserved mucsoal folds toward the proximal margin. The areas of diffuse abnormality with blackened thinned mucosa are estimated to involve an approximate 460 mm length of bowel.  Within the large bowel, there is a range of appearances. The distal 30mm of mucosa is tan and unremarkable; proximal to this and involving a 110mm segment of bowel, there are prominent vertical serpentine mucosal folds lending a polypoid appearance to the mucosa.  There are also 3 adjacent diverticula, associated with thinning of the bowel wall.  Within an approximate 55x50mm area of the cecum and involving the ileocecal valve, the mucosa is nodular and friable. Part processed.

Microscopy: Sections through small and large bowel show patchy mucosal ischemic change with foci of mucosal and partial thickness mural ischemic infarction extending to involve the luminal half of the muscularis propria.  Colonic sections show evidence of diverticular disease.  At one diverticulum (Block A3), there is transmural ischemic necrosis associated with transmural active inflammation and peridiverticular abscess formation.  There is a florid active serositis.  Convincing evidence of a primary vasculitic process is not identified, nor is intramural amyloid deposition seen.  Intravascular thromboemboli are not identified.  Pericolic lymph nodes show variable sinusoidal expansion by neutrophils in keeping with acute lymphadenitis.  Changes of patchy mucosal ischemia extend to the proximal and distal margins of the specimen.  There is no evidence of dysplasia or malignancy.

Conclusion: Right hemicolectomy specimen, showing: (i) Small and large intestinal ischemic change, ranging from mucosal ischemia to partial and,  focally, full thickness mural ischemic infarction, the latter occurring at a colonic diverticulum and associated with peri-diverticular abscess formation and florid active serositis. (ii) Colonic diverticular disease.