Extracolonic gastrointestinal tract morphologic findings in a case of pseudomembranous collagenous colitis.

"Pseudomembranous collagenous colitis" is a morphologic variant of collagenous colitis in which active inflammation with pseudomembrane formation is prominent and which has been associated with infectious, toxic, and ischemic etiologies. However, extracolonic morphologic findings in patients with pseudomembranous collagenous colitis have not been previously described. Here, we present a case of a patient with pseudomembranous collagenous colitis with abnormal extracolonic findings. These include gastric antral mucosa with histologic features reminiscent of ischemic injury and reactive gastropathy with intraepithelial lymphocytosis and partial villous atrophy in the duodenal and ileal biopsies. The findings in the small intestinal biopsies resemble those seen in enteric mucosa in patients with conventional collagenous colitis. Our pathologic findings as well as the clinical course of the patient further emphasize the clinical and histologic similarities shared by pseudomembranous collagenous colitis and conventional collagenous colitis.