Original ArticlesCharacteristics and Outcomes of Left-sided Ulcerative Colitis With a Cecal/Periappendiceal Patch of InflammationAlbayrak, Nazire E. MD; Polydorides, Alexandros D. MD, PhD Author Information Department of Pathology, Molecular, and Cell-based Medicine, Icahn School of Medicine at Mount Sinai, New York, NY Conflicts of Interest and Source of Funding: The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article. Correspondence: Alexandros D. Polydorides, MD, PhD, Department of Pathology, Molecular and Cell-based Medicine, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1194, New York, NY 10029 (e-mail: [email protected]). The American Journal of Surgical Pathology: August 2022 - Volume 46 - Issue 8 - p 1116-1125 doi: 10.1097/PAS.0000000000001883 Buy SDC Metrics Abstract Ulcerative colitis (UC) is characterized by continuous mucosal inflammation of the rectum, extending uninterrupted to a variable portion of the colon proximally. However, in some patients with distal colitis, a distinct pattern of skip inflammation (so-called patch) involves the cecum and/or appendiceal orifice, but data on this entity are contradictory, and its significance and prognosis are still debated. We identified 102 adult cases of left-sided UC with a cecal/periappendiceal patch and compared them to 102 controls (left-sided UC only) along clinicopathologic characteristics and disease outcomes. In multivariate analysis, patients with a patch were younger (median age: 31 vs. 41 y; P=0.004) and more likely to have rectosigmoid involvement only (58.8% vs. 28.4%; P<0.001), compared with patients without a patch. During follow-up, patients with a patch were more likely to be eventually diagnosed with Crohn disease (CD) (9.8% vs. 1.0%; P=0.022) and to show proximal extension of inflammation (35.6% vs. 10.0%; P=0.021), but showed no differences in rates of neoplasia, colectomy, or pharmacotherapy escalation. Kaplan-Meier analysis confirmed that patients with a biopsy diagnosis of cecal/periappendiceal patch were more likely to show proximal disease extension (P<0.001) and to be diagnosed with CD (P=0.008). In conclusion, cecal/periappendiceal skip inflammation in left-sided UC occurs more often in younger patients and in those with rectosigmoid involvement and is associated with proximal disease extension and, in a small fraction of cases, change of diagnosis to CD. However, it does not portend increased risk of neoplasia, pharmacotherapy escalation, or subsequent colectomy, compared with patients with left-sided UC only. Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.