Slide 1
Gross: This colectomy was performed for idiopathic ulcerative colitis. The mucosa is hyperemic, friable, and granular due to capillary dilatation and congestion in the lamina propria. The entire colon from the cecum to the anus is involved, a presentation which gastroenterologists refer to as universal colitis or pancolitis. About 1/2 of patients with ulcerative colitis will have pancolitis: the remainder will have disease limited to the left colon and rectum.

Slide 2
Is a low power view of the example of early ulcerative colitis in your class set. The changes which you need to see are limited to the mucosa (M). The large round purple structures present in the submucosa, two of which are marked with arrows, are lymphoid aggregates.

Slide 3
Is a higher magnification of the mucosa and submucosa. There is marked chronic inflammation which is largely limited to the lamina propria of the mucosa and only focally spills across the muscularis mucosa to involve the submucosa (large arrow). Notice that many of the colonic crypts are dilated (skinny arrows).