A 37-year-old woman presented with an acute abdomen following the onset of
watery diarrhea. Spontaneous peritonitis was detected, along with evidence
of a focal sigmoid colon perforation. Subsequent postoperative colonoscopic
studies revealed collagenous colitis with a focal, deep, nongranulomatous
ulcer in the sigmoid colon. Although the literature suggests that collageno
us colitis tends to have a relatively 'benign' clinical course characterize
d by chronic or episodic watery diarrhea. Potentially serious and life-thre
atening complications may occur in this microscopic form of inflammatory bo
wel disease.