The importance of magnification chromoendoscopy with methylene blue in detecting specialized intestinal metaplasia in short segment Barrett’s esophagus

Background Barrett esophagus is an acquired, premalignant condition caused by chronic gastroesophageal refllux, in which the normal squamous epithelium in the distal esophagus is replaced by columnar epithelium. Barrett’s esophagus is considered to follow a multistep process progression from intestinal metaplasia to low-grade dysplasia (LGD) to high-grade dysplasia (HGD) and finally to esophageal invasive adenocarcinoma in a subset of patients (Hameeteman et al 1989; Miros et al 1991). In epidemiologic studies, BE is associated with an increased risk of esophageal adenocarcinoma (EAC), at least 40-fold higher than the general population (Drewitz et al 1997; Spechler et al 1984). The risk of developing EAC among patients with BE is estimated between 0.5% and 1% per patient per year (Falk 2002). The diagnosis of BE relies initially on the endoscopic recognition of the columnar lined distal esophagus and is confirmed by histological examination. The metaplastic Barrett epithelium is a mosaic of different types of columnar epithelium which frequently coexist in the same patient (Paull et al 1976): cardial, fundic and specialized intestinal metaplasia (SIM) with goblet cells. Due to the identification of histologically confirmed SIM as a precursor lesion for dysplasia and malignancy, obtaining biopsies from the columnar lined distal esophagus is mandatory (Chalasani et al 1997; Schnell et al 1992). Even if columnar metaplasia in the distal esophagus can be easily recognized as a displacement of scuamocolumnar junction over the gastroesophageal junction, it is difficult to identify SIM in standard endoscopy. The most widely accepted method to identify the presence of SIM in standard endoscopy is the use of four-quadrant random biopsy at 1-2 cm intervals over the entire length of the specialized columnar epithelium. This protocol, referred to as the Seattle protocol, has certain disadvantages and limitations: use of multiple biopsies, sampling errors, long time procedure because of the number of biopsies and high cost (Sampliner 1998; Falk et al 2000). Because of the reminded limitations of the Seattle protocol, several techniques that could improve recognition of SIM and provide a more accurate way to guide biopsies have been tried. Abstract. Background:S pecialized intestinal metaplasia (SIM) is not identifiable in Barrett esophagus in standard white light endoscopy. In this study we assessed the utility of magnification chromoendoscopy with methylene blue in detecting SIM in patients with short Barrett’s esophagus. Material and method: The study included 50 patients with suspected short Barrett’s esophagus: 26 followed standard endoscopy with random biopsies and 24 underwent magnification chromoendoscopy with methylene blue with targeted biopsies. In the magnification chromoendoscopy group, magnified images were analyzed and specific patterns were classified using Endo’s classification. Results: In the standard endoscopy group, 17 of 26 patients were detected as having SIM and in the magnification chromoendoscopy group 20 of 24 patients were SIM positive. Magnification chromoendoscopy increases the probability of detecting SIM up to 2,4 times (OR=2.39, p=0.028). Sensitivity and specificity of MB staining in diagnosis of SIM was 78.7% and 55.5%. SIM was diagnosed in areas with tubular and villous patterns, but had a significant correlation only with villous pattern (p=0.017). Conclusion: Magnification chromoendoscopy with methylene blue improves SIM detection in patients with short Barrett’s esophagus.