Microscopic Colitis: Not Always “Microscopic”

80-year-old patient with ongoing watery diarrhea for several weeks. Colonoscopy images shown here. Note that there is significant patchy edema, hypervascularity, punctate erythema, thickened folds and patchy superficial erythema.

Classically, microscopic colitis (collagenous and lymphocytic) is thought to have normal colon mucosa, but several studies now have shown that many patients have abnormal colon mucosal findings, such as the ones depicted in our case (1-3). The best review on the topic was written by A. Kolaouzidis and A. Saeed (1). The authors performed a systematic electronic and manual search of PubMed and EMBASE for publications on distinct endoscopic findings in microscopic colitis, resulted in 42 relevant reports for inclusion in this review (1). The authors found four broad categories of distinct endoscopic findings in collagenous colitis: (1) pseudomembranes; (2) mucosal vascular pattern alteration which includes an indistinct appearance of the blood vessels and a variable degree of pruning of the mucosal vasculature, or a crowded, dilated and tortuous capillary network; (3) mucosal abnormalities such as red spots and some mucosal nodularity or textural alteration, evident with or without chromoendoscopy and (4) a continuum of mucosal breaks/defects, i.e., mucosal lacerations/tears, including the so-called “cat scratch colon” pattern, or fractures usually along the long axis of the colonic wall to the fine linear cicatricial lines or thick scar-like ridges of the mucosal surface (effects of the mucosal healing process of mucosal defects) (1).

Interestingly, they only found one publication describing a characteristic endoscopic pattern in lymphocytic colitis. Thus, our case adds to the growing literature on “macroscopic” endoscopic changes in “microscopic colitis”.

References:

1. Koulaouzidis A, Saeed AA. Distinct colonoscopy findings of microscopic colitis: not so microscopic after all? World J Gastroenterol. 2011 Oct 7;17(37):4157-65. doi: 10.3748/wjg.v17.i37.4157. PMID: 22072846; PMCID: PMC3209563.

2. Wickbom A, Lindqvist M, Bohr J, Ung KA, Bergman J, Eriksson S, Tysk C. Colonic mucosal tears in collagenous colitis. Scand J Gastroenterol. 2006 Jun;41(6):726-9. doi: 10.1080/00365520500453473. PMID: 16716973.

3. Park HS, Han DS, Ro YO, Eun CS, Yoo KS. Does lymphocytic colitis always present with normal endoscopic findings? Gut Liver. 2015 Mar;9(2):197-201. doi: 10.5009/gnl13373. PMID: 25167800; PMCID: PMC4351026.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4351026/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4351016/

About the authors

Joel Joseph, MD

Gastroenterologist

Lexington Medical Center, West Columbia, South Carolina, USA

Joel Joseph, MD, is a board-certified gastroenterologist practicing in West Columbia, South Carolina, and affiliated with Lexington Medical Center. He earned his medical degree from the Medical College of Georgia at Augusta University in 2018 and completed his gastroenterology fellowship at Carilion Clinic / Virginia Tech Carilion School of Medicine in 2025.

Troy Pleasant, MD

Gastroenterologist

RMG Gastroenterology, Raleigh, North Carolina, USA

Troy Pleasant, MD, is a gastroenterologist with RMG Gastroenterology in North Carolina. He earned his medical degree from Eastern Virginia Medical School, completed internal medicine residency at Wake Forest Baptist Hospital in Winston-Salem, and completed his gastroenterology fellowship at Carilion Clinic / Virginia Tech in 2025. His clinical interests include colorectal cancer screening, inflammatory bowel disease, IBS, and esophageal disorders.

Klaus Mönkemüller, MD, PhD, FASGE, FJGES, FESGE

Editor-in-Chief, The Practicing Endoscopist

Professor of Medicine, Carilion Memorial Hospital / Virginia Tech Carilion School of Medicine, Roanoke, Virginia, USA

Klaus Mönkemüller, MD, PhD, FASGE, FJGES, FESGE, is the editor-in-chief of The Practicing Endoscopist and the founder of EndoCollab. He is Professor of Medicine at Virginia Tech Carilion School of Medicine and a practicing endoscopist at Carilion Memorial Hospital in Roanoke, Virginia.

Dr. Mönkemüller has published extensively on endoscopic techniques and devices, with a particular focus on therapeutic endoscopy, foreign body removal, GI bleeding, and the use of caps and accessories in everyday practice. He lectures internationally and has contributed to multiple GI endoscopy textbooks and atlases.

Save this article as a PDF

Drop your email and we'll open a print-ready version you can save as a PDF — and you'll start getting our weekly GI endoscopy newsletter.

← All articles