<正>To the editor:Pyoderma gangrenosum(PG)is an idiopathic inflammatory disease of unknown etiology,frequently associated with underlying systemic conditions such as inflammatory bowel disease(IBD)including ulcerative colitis(UC)and Crohn's disease,rheumatologic disease or malignancy.1PG associated with UC and psoriasis in the same patient is rare.Here we report a case simultaneously incurring with three entities.