Obstructive enterocolitis: a clinico-pathological discussion.

Obstructive colitis is a condition that is not widely appreciated by pathologists. It is defined as an ulcero-inflammatory lesion(s) proximal to a colonic obstruction from which it is separated by a variable length of normal mucosa. Five cases are described which illustrate the clinico-pathological spectrum of the condition. All presented surgically as acute intestinal obstruction, secondary to adenocarcinoma in four cases and a diverticular stricture in one case. Pathologically, the severity of colitis ranged from a single discrete ulcer to an extensive area of fulminant colitis indistinguishable from colitis indeterminate. Furthermore, two cases represented 'obstructive enteritis', a variant of obstructive disease not previously reported. Microscopically, all cases were characterized by distinctive areas of localized ulceration and active inflammation, the features of which were quite unlike those of Crohn's disease or ischaemia, separated by islands of normal mucosa. The role of mural hypoperfusion and secondary localized ischaemia in the pathogenesis of this disorder is discussed. It is suggested that colitis indeterminate represents the final common pathological pathway of the intestine to a wide range of initial insults, be they obstructive or inflammatory.