<prompt> Pyoderma gangrenosum is seen in :Crohns diseaseDiveuculosisUlcerative colitisCa. Colon  <response>: C. i.e. Ulcerative colitis Pyoderma gangrenosum occurs in both ulcerative colitis Crohns diseaseQ. But - 50 of PG occurs in association with UC. And - 2 of active UC patients have PG and another 4 UC patients have erythema nodosum. The mean duration of chronic ulcerative colitis before the appearance of erythema nodosum PG is 5 10 years respectively. 