Following the very short course of a disease with watery diarrhea, fev
er, nausea, meteorism and a severe feeling of general illness, a 22-ye
ar-old patient was diagnosed as having a toxic megacolon, and a subtot
al colectomy was carried out. The postoperative progression was uncomp
licated and the patient recovered quickly. The examination of the oper
ation specimen revealed a serious ulcerous colitis with relative omiss
ion of the rectum and the distal sigmoid colon. After critical evaluat
ion of the histological findings, it was judged to be a fulminant Croh
n's colitis and: for the purposes of differential diagnosis, different
iated from ulcerative colitis and colitis indeterminate. The formal pa
thogenesis of the inflammatory-ulcerous processes is discussed, in par
ticular with regard to the activation of the macrophages and the very
short anamnesis in a clinically established primary manifestation of t
he disease.