surgpathcriteria.stanford.edu/gi/ulcerative-colitis/printable.htmlAs this article states patchy UC is rare - but it does happen.
I was diagnosed with "patchy" ulcerative colitis ten years ago. Although on my latest colonoscopy the diagnosis is now pancolitis it's still patchy. At the moment most of my UC is in remission but I have a patch of ulcers on the RHS. Sometimes I have ulcers on the left and a patch at the caecum. My biopsies support the diagnosis of UC to date.