[735] Counting Colonic Mast Cells Is Not Diagnostically Useful in Patients with Chronic Diarrhea of Unknown Etiology

Aisha Sethi, Dhanpat Jain, Banie Chander, Jason Kinzel, Joanna Gibson, Ronald Schrader, Joshua A Hanson. University of New Mexico School of Medicine, Albuquerque, NM; Yale University School of Medicine, New Haven, CT

Background: Mastocytic Enterocolitis (ME) is a recently described entity defined by chronic diarrhea of unknown etiology (CDUE) and normal GI biopsies with increased mast cells (MC) seen on special stains. Recent data suggest that patients with ME may benefit from MC stabilizers. This has led some authors to recommend MC stains in the work up of patients with CDUE. The current study represents the largest to date examining the diagnostic utility of colonic MC in patients with CDUE.
Design: Blinded MC counts using a c-kit stain were performed in 76 patients with CDUE who had normal colon biopsies and in 89 asymptomatic controls presenting for screening colonoscopy who had biopsies of normal colonic mucosa. MC were counted per single high power field (hpf) in the highest density area. A t-test was used to compare the counts and a receiver operating characteristic (ROC) curve was generated to determine if increased MC counts are a sensitive and specific marker of disease.
Results: For all colon biopsies independent of site, the study group averaged 31 MC/hpf (SD = 10.50) versus 24 MC/hpf in the control group (SD = 8.6, p<0.0001). When biopsies were stratified by location, a significant increase was seen in biopsies from the left but not right colon. ROC analysis revealed that MC counts do not yield a diagnostically accurate cutoff value (AUC = 0.68).

Left Colon
GroupNMeanStd. Dev.p-value 

Right Colon
GroupNMeanStd. Dev.p-value

Conclusions: Although the absolute differences are small, MC counts are significantly increased in patients with CDUE, primarily in the left colon. In addition, ROC analysis shows that there is no cutoff value that would be considered diagnostically accurate. Therefore, from a testing standpoint, performing MC stains on normal colon biopsies in patients with CDUE yields little useful information. Further case controlled studies are necessary to determine if ME truly represents a distinct disease entity.
Category: Gastrointestinal

Monday, March 4, 2013 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 115, Monday Morning


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