[Difficulties in differentiation between Crohn disease and ulcerative colitis].

We report on the medical history of a 44 year old woman, who has been diagnosed to suffer from ulcerative colitis, first diagnosed in 1991. Until 1994, when she had finally a colectomy, recurrent episodes occurred under full medical treatment. After colectomy the diagnosis had to be revised as histology revealed Crohn's disease. Only a few months after surgery a new episode of Crohns disease developed including the occurrence of an anal fistula.