Pseudo-pseudomembranous collagenous colitis ▸

Microscopic colitis has been divided into three types (

), all characterised by watery diarrhoea and minimal mucosal changes at colonoscopy, associated with an increase in lamina propria lymphocytes and minimal crypt architectural distortion. Of the three types, lymphocytic colitis also has an increase in intraepithelial lymphocytes, collagenous colitis has a subepithelial collagen band, and microscopic colitis not otherwise specified has neither. A form with giant cells has also been described and types may evolve from one to another (very rarely to ulcerative colitis) in the same patient. Now, along comes another variant—pseudomembranous collagenous colitis—and the question arises as to whether or not it is a true bill. This case series of 10 patients describes collagenous colitis with pseudomembranes (neutrophils, fibrin, and debris). Cases were gleaned from pathology records of distinguished pathology departments in Seattle and Connecticut over a 10 year period. Only one case was associated with Clostridium difficile toxin but results were unavailable in 4/10 cases. Very limited clinical and colonoscopic data are available. …