[A case of ulcerative colitis with preexisting idiopathic thrombocytopenic purpura].

A 53-year-old man was diagnosed as having idiopathic thrombocytopenic purpura (ITP). Hematochezia appeared under steroid therapy for ITP after the diagnosis of ITP 18 months. Colonoscopic study demonstrated inflamed rectal mucosa but there was no evidence of infectious colitis. The colonoscopic and pathological findings were compatible with ulcerative colitis (UC). There have been a few reports of patients with UC complicated by ITP, but in all except one report, UC preceded ITP. This is the third case in which ITP preceded UC and the first case in which the proctitis type of UC was complicated by ITP in Japan.