crohn's colitis is CD affecting the colon..."col"=colon "itis"=inflammation...
No, it's not restricted to the colon forever, CD can affect more than one area at a time (and often does), it can appear in the colon, get better and then appear in the small intestines (it kinda can have a mind of it's own).
pancolitis means the entire colon is inflammed and this is common with UC more so than crohn's because of the fact that crohn's typically has patchy inflammation with healthy tissues in between, where as with UC the entire area within the colon will be inflammed, even if it's just one area of the colon, with pancolitis the entire colon is inflammed which is why it's related to UC and not crohn's.
My bum is broken....there's a big crack down the middle of it! LOL :)