Quantitative Analysis of Intramucosal Mast Cells in Irritable Bowel Syndrome: A Comparison With Inflammatory Bowel Disease in Remission.

GOAL: We aimed to study the density of intramucosal mast cells in histologically normal colonic mucosa biopsied from patients with a clinical diagnosis of irritable bowel syndrome (IBS). BACKGROUND: Mast cell activation has been thought to implicate in the pathogenesis of inflammatory bowel disease (IBD). Whether it serves a role in the pathogenesis of IBS remains controversial. STUDY: A total of 127 colonoscopic mucosal biopsies were immunohistochemically stained, including 51 IBS, 66 IBD, and 10 normal control samples. Intact mast cells were quantified in 3 high power fields (HPF) in areas showing the highest density. RESULTS: CD117 was sensitive in detecting mast cells in colonic mucosa. The mast cell counts in all biopsies ranged from 2 to 60 per HPF (mean=17.5±7.2). The density of intramucosal mast cells were similar among IBS, IBD and normal control groups (P=0.6733). IBD in remission versus IBS (17.1±8.0 vs. 18.1±7.0; P=0.4804), Crohn disease versus ulcerative colitis (17.1±10.4 vs. 17.2±5.2; P=0.9463), IBS with diarrhea versus without diarrhea (19.5±6.3 vs. 16.8±6.9; P=0.1404). Forty biopsies (31.5%) showing ≥20 mast cells per HPF appeared to equally distribute among various disease groups (P=0.7283). CONCLUSIONS: There is no significant difference in the number of intramucosal mast cells between IBS and IBD that show normal colonic biopsies. In IBS patients, the number of intramucosal mast cell does not correlate with symptoms. The mast cell count (≥20/HPF) is not a reliable criterion for the diagnosis of IBS or for the distinction between patients with IBS and those with IBD in remission.

Value of SATB2 immunostaining in the distinction between small intestinal and colorectal adenocarcinomas.

AIMS: Special AT-rich sequence-binding protein 2 (SATB2) is a novel immunomarker that is expressed in glandular cells of the lower gastrointestinal tract with retained expression in the majority of primary and metastatic colorectal adenocarcinomas (CRCs). Because of its tissue specificity, SATB2 has been shown to be a clinically useful marker to distinguish CRC from non-CRC. In this study, we investigated whether or not SATB2 can help differentiate CRC from small intestinal adenocarcinoma (SIA), a practical diagnostic challenge due to their morphological and immunophenotypic similarities. METHODS: Fifty surgically resected primary SIAs and 50 CRCs were immunohistochemically examined for the expression of SATB2. Positive staining was graded as 1+ (5-25% of the tumour cells stained), 2+ (26-50%), 3+ (51-75%) or 4+ (>75%), as well as weak, intermediate or strong for staining intensity. RESULTS: Positive SATB2 immunoreactivity was observed in 23 (46%) SIAs in contrast to 48 (96%) CRCs (p<0.0001). Among these, only 4 (8%) SIAs showed strong and diffuse (4+) SATB2 staining compared with 38 (76%) of CRCs (p<0.0001). CONCLUSIONS: SATB2 is not entirely CRC-specific and is expressed in a subset of SIAs. Unlike CRC, however, SIA infrequently shows a strong and diffuse staining pattern, which still makes SATB2 a useful immunomarker to distinguish SIA from CRC.