Pitfalls in Ileal Pouch and Rectal Cuff Biopsy Analysis: Utility of CD10 Expression
GH Tozbikian, EE Furth. Hospital of the University of Pennsylvania, Philadelphia, PA
Background: Total proctocolectomy with ileal pouch-anal anastomosis (IPAA) is a surgical option for patients with ulcerative colitis (UC). Accurate directed biopsies for the IPAA and rectal cuff are important to assess for inflammation and neoplastic development, respectively. However, there is often confusion as to biopsy locale due to the overlapping clinical symptoms and endoscopic features of pouchitis and UC in the rectal mucosal remnant cuff (cuffitis). Our goal was to utilize the expression of Neprilysin (CD10), a membrane metallopeptidase localized to the luminal brush border of the small bowel and not expressed in and colonic/rectal epithelium, to determine the frequency of errors in biopsy localization.
Design: CD10 expression was scored (binary scale) in biopsies as designated at the time of endoscopy (32 IPAA (15 with accompanying adjacent rectal cuff biopsies)) as well in control specimens (7 normal colon, 6 normal small bowel, 10 UC colon and their ileum, 9 Crohn disease (CD) small bowel, and 6 CD colon). Architecture distortion and inflammation were scored as absent or present and 0-3, respectively.
Results: All normal and diseased colon controls lacked CD10 expression while all normal and diseased small bowel epithelium equally expressed CD10 showing inflammation did not alter its expression. 9 of 15 cases designated “rectal cuff” were CD10 positive and 4 of 32 cases designated “IPAA” lacked CD10 expression; thus, the prevalence of errors in endoscopic localization was 60% for “rectal cuff” and 13% for “IPAA” biopsies. The frequency of CD10 expression in “rectal cuff” biopsies was significantly less than normal colon, UC colon, CD colon and CD normal small intestine (p<0.05). CD10 negative pouch biopsies had higher inflammatory scores and incidence of crypt architecture distortion compared to CD10 positive biopsies (2.6 vs 1.6, 100% vs 70%).
Conclusions: Possible errors in endoscopic localization and histopathologic designation of biopsies from 60% of rectal cuff and 13% of ileal pouch biopsies were found based upon CD10 expression as a marker for small bowel epithelium. Because continued surveillance of the rectal cuff for dysplasia is critical in patients with UC, accurately directed biopsies to this area is needed. Evaluating for CD10 expression may be a useful tool to assure proper biopsy classification.
Monday, March 22, 2010 9:30 AM
Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 112, Monday Morning