[Unusual form of ulcerative colitis].

Segmental colitis which showed the similar findings of ulcerative colitis and right-sided colitis with back-wash ileitis has been considered as the unusual form of ulcerative colitis. Today, we have few opportunities to come across those cases, because modern diagnosis of colon disease could make differential diagnosis easily with the sense of broad spectrum of IBD. We presented three cases of segmental colitis and one case of so-called indeterminate colitis associated of carcinoma in the cecum and discussed the clinical significance for diagnosis and finding the step of studying the etiology of IBD. Especially, in the third case, thirteen years old man was showing the sign of early stage of Crohn disease with non-caseating granuloma in the biopsy specimen at first, the findings of the segmental ulcerative colitis with crypt abscess were seen after six months in the second examination. To observe the detail changes of the mucosal lesion in this kind of cases will present the new idea for studying the etiology of IBD.