[664] Caveat Emptor: CD10 Is Not a Reliable Marker of Inflamed Small Intestine.

Joshua M Lloyd, Scott R Owens. UPMC, Pittsburgh, PA

Background: Ileal pouch-anal anastomosis (IPAA) is a surgical option in patients who undergo total proctocolectomy, often in the setting of ulcerative colitis (UC). IPAA patients are followed clinically for pouchitis as well as for residual UC in the remnant rectum. Distinction between the two is important; pouchitis is treated with antibiotics, while rectal UC may need more aggressive treatment and can develop colitis-associated dysplasia. Crohn's ileitis (CI) may enter the differential diagnosis in patients with severe pouchitis. Inflammatory changes in the small intestinal (SI) mucosa can make it difficult to identify mucosa as being ileal or colonic. CD10 is a cell surface metalloproteinase expressed by small intestinal brush border. Its role in the evaluation of biopsies in IPAA patients has only been rarely examined. This study aims to determine the utility of CD10 immunohistochemistry (IHC) in identifying SI mucosa in the setting of inflammation.
Design: CD10 expression was determined by IHC (clone 56C6; Ventana, Tucson, AZ) on formalin-fixed, paraffin-embedded tissue from surgical resections and endoscopic biopsies in a variety of clinical scenarios. CD10 was scored as positive (complete luminal staining), negative, or patchy, and percent of the epithelium with loss of staining was recorded. The presence or absence of active inflammation was noted.
Results: All (35) colonic specimens were negative for CD10. 27/68 (40%) SI specimens had patchy staining. 6/6 normal SI and 3/3 normal ileocecal valve had uniformly positive CD10 staining. 1/12 (8%) ileostomy (without CI), 1/6 (17%) enteroenteric anastomosis (EEA; without CI), 3/7 (43%) ileocolonic anastomosis (ICA; without CI or UC), 7/16 (44%) ileal pouch, 6/8 (75%) backwash ileitis (BWI), and 9/10 (90%) CI cases had patchy staining. Percentage of CD10 loss varied from 20-90% in BWI (mean=55%; all with active inflammation), 10-50% in pouches (mean=36%; all with active inflammation), and 10-80% in CI (mean 32%; all with active inflammation). In the ileostomy with patchy staining, there was <10% loss and active inflammation. The 3 ICA all had <10% loss and 1/3 had active inflammation. The EEA had 10% loss and active inflammation. Loss of staining was accentuated in intact epithelium surrounding ulcers.
Conclusions: While CD10 is a reliable marker of SI mucosa in the absence of inflammation, caution must be exercised when interpreting CD10 IHC in inflamed mucosa, especially when biopsy material is limited. SI mucosa seems particularly susceptible to CD10 loss in the microenvironment of BWI, suggesting that the mucosa in this setting may be undergoing phenotypic alteration.
Category: Gastrointestinal

Tuesday, March 1, 2011 1:00 PM

Poster Session IV # 57, Tuesday Afternoon


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