<prompt> True regarding ulcerative colitis is ?Involves only mucosaInvolves perianal regionSkip lesion seenMost commonly involve small intestine  <response>: Ulcerative colitis is a disease of the rectum and colon. In ulcerative colitis colonic inflammation is diffuse, confluent and superficial, primarily affecting the mucosa and superficial mucosa. Skip lesions are seen in Crohns disease. Reference : Bailey Love 27th Edition, page no 1267. 