228 Variability in Colonic Eosinophilia in 277 Consecutive Patients

Abstract

INTRODUCTION: There is no acceptable method for the histopathologic evaluation and reporting of eosinophils (Eos) in colorectal biopsies because there is no agreement among pathologists as to what constitutes an abnormal finding. This study evaluated differences in Eos count relative to known clinical and pathologic features. METHODS: H&E slides from 277 subjects who underwent colonoscopy with biopsies were reviewed. Eos/mm 2 were counted in the area with highest concentration then correlated with clinical and pathologic findings. Normal histology (NL) was defined as biopsy without significant histopathologic changes. RESULTS: There were higher numbers of Eos/mm2 in the right colon than the left colon and rectum (mean 177 vs 122, respectively P < 0.0001). In the right colon, the mean Eos/mm2 was higher with pathologic diagnosis of colitis (P < 0.001), males (204 vs 164, P = 0.022), abnormal endoscopy (208 vs 148, P < 0.001), and ulcerative colitis (UC) (226 vs 158, P < 0.001), but lower with history of abdominal pain (158 vs 208, P = 0.003) and IBS-D (130 vs 185, P = 0.023). In the left colon and rectum, mean Eos/mm2 was higher with pathologic diagnosis of colitis (P < 0.001), males (154 vs 107, P < 0.001), abnormal endoscopy (155 vs 92, P < 0.001), and a diagnosis of UC (192 vs 95, P < 0.001) but lower with history of abdominal pain (108 vs 145, P = 0.003) and IBS-D (83 vs 128, P = 0.010). In NL biopsies, the right colon showed higher mean Eos/mm2 in Asians (228 vs 139, P = 0.019), and diagnosis of UC (205 vs 136, P = 0.004) but was lower with abdominal pain (132 vs 167, P = 0.028), and did not show significant differences with history of IBS-D, Chron's disease (CD), or abnormal endoscopy. In the left colon and rectum the mean Eos/mm2 with higher in males (102 vs 77, P = 0.036), and a diagnosis of CD (117 vs 78, P = 0.007) but did not show significant differences with history of UC, abdominal pain, IBS-D, or abnormal endoscopy. CONCLUSION: The mean number of Eos/mm2 in colorectal biopsies varies significantly by location, associated histopathologic changes, and clinical diagnosis, and is also influenced by sex. Of particular interest is the association between high Eos/mm2 in right colon biopsies with otherwise normal histology and diagnosis of UC and in left colon and rectum biopsies with history of CD. Additional larger studies are needed to define the significance of colorectal eosinophil counts in clinical practice.