Massive mural edema in severe pseudomembranous colitis.

Three patients had severe acute pseudomembranous colitis due to Clostridium difficile toxin and required surgical resection. In addition to the characteristic mucosal lesions, the colonic specimens showed a marked degree of diffuse mural edema that extended into the muscularis propia and involved areas of the colon with and without pseudomembranes. To our knowledge, such extreme edema has not been previously noted in pathologic descriptions of this disorder; it may possibly result from a toxic effect on the vessels combined with a large parenteral fluid replacement. Lesser degrees may be seen in other forms of acute colitis, but it would appear that the presence of massive and diffuse mural edema is most typical of Clostridia-associated colitis. The detection of such edema in a case of acute colitis should prompt an investigation for antibiotic usage and C difficile toxins.