Intestinal metaplasia in Barrett's oesophagus may be an epiphenomenon rather than a preneoplastic condition, and CDX2-positive cardiac-type epithelium is associated with minute Barrett's tumour.

AIMS: Although intestinal-type epithelium in Barrett's oesophagus has been traditionally recognized as having a distinct malignant potential, whether this also holds true for cardiac-type epithelium remains controversial. The aim of this study was to identify a type of epithelium that is highly associated with Barrett's tumour. METHODS AND RESULTS: We analysed tumours and the corresponding background mucosa with special regard to tumour size in 40 cases of superficial Barrett's tumour by using immunohistochemical staining for CDX2, CD10, MUC2, MUC5AC, and MUC6. Intestinal metaplasia in tumour-adjacent mucosa was not associated with tumour size, but was significantly correlated with the extent of Barrett's oesophagus (P < 0.001). The majority (69.2%, 9/13) of small tumours (≤10 mm) had no intestinal metaplasia in adjacent non-neoplastic mucosae. Minute (≤5 mm) tumours were significantly associated with a gastric immunophenotype (P < 0.001). Purely gastric-immunophenotype tumour cells expressed CDX2, and cardiac-type epithelium adjacent to small tumours also showed low-level CDX2 expression. CONCLUSIONS: Our data suggest that intestinal metaplasia in Barrett's oesophagus is an epiphenomenon rather than a preneoplastic condition, and that CDX2-positive cardiac-type epithelium is highly associated with minute Barrett's tumour. Further prospective studies are needed to evaluate the risk of malignancy of cardiac-type epithelium with regard to sub-morphological intestinalization.

Alpha-methylacyl-coenzyme A racemase expression in neuroendocrine neoplasms of the stomach.

The enzyme alpha-methylacyl-coenzyme A racemase plays an important role in the beta-oxidation of branched-chain fatty acid and its derivatives. It has been used to detect prostatic adenocarcinoma and high-grade intraepithelial neoplasia, and recently also as a marker for other neoplasms, including those of the genitourinary system, breast, upper and lower gastrointestinal tract and their precursor lesions. We assessed expression of alpha-methylacyl-coenzyme A racemase by immunohistochemistry in neuroendocrine tumours of the stomach to determine differences in the incidence and pattern of expression among different types of gastric neuroendocrine tumours. While none of the grade 1 neuroendocrine tumours were immunoreactive, 67 % of grade 2 neuroendocrine tumours and 90 % of neuroendocrine carcinomas were positive for alpha-methylacyl-coenzyme A racemase. Furthermore, an adenocarcinoma component was found in 72.5 % (37 of 51) of neuroendocrine carcinomas, whereas none of the grade 1 and 2 neuroendocrine tumours contained an adenocarcinoma component. In 83 % of neuroendocrine carcinomas, the adenocarcinoma component was positive for alpha-methylacyl-coenzyme A racemase, and both adenocarcinoma and neuroendocrine carcinoma components stained positively in 78 % of these cases. Our results indicate that alpha-methylacyl-coenzyme A racemase is a useful marker for distinguishing between grade 1 (negative) and grade 2 neuroendocrine tumours, and neuroendocrine carcinoma of the stomach (frequently positive). Different patterns of alpha-methylacyl-coenzyme A racemase expression between gastric neuroendocrine tumours and neuroendocrine carcinoma suggest that these might develop via different tumourigenic pathways.