[Cytokeratin 7 and 20 in Barrett's esophagus]

Barrett's esophagus (BE) has been identified as the most important risk factor for adenocarcinoma of the distal esophagus. BE has been categorized as long-segment (LSBE) if it extends 3 cm or more up the esophagus and as short-segment (SSBE) if it extends less than 3 cm into esophagus. Intestinal metaplasia may also develop in gastric mucosa (IMG) at the gastroesophageal junction. IMG has a much lower risk to progress to dysplasia or carcinoma when compared with SLBE or SSBE. Moreover, these conditions are difficult to distinguish one from another only based on endoscopic and morphologic criteria. Therefore the aim this study was to evaluate the cytokeratin (CK) 7 and 20 inmunoreactivity patterns in these intestinal metaplasias with the purpose to determine the precise anatomic site of the biopsy. Biopsy specimens from 14 patients with LSBE, 6 with SSBE and 7 patients with IMG were inmunohistochemically stained with monoclonal antibodies to CK 7 and 20. Barrett's CK7/20 pattern was characterized by superficial and deep CK7 reactivity and only superficial CK 20 staining in the intestinalized mucosa. This pattern was found in all 7 (100%) patients with LSBE, and was absent in all 7 patients with IMG. All biopsy specimens from patients with IMG showed no staining for CK7 and diffuse surface positivity for CK20. 67% of the biopsy specimens from patients with endoscopic SSBE showed Barrett's CK7/20 pattern, and the remaining 33% specimens showed the IMG staining pattern. Based on our data the inmunohistochemical determination of CK7/20 is an excelent tool with high specificity in distinguishing LSBE and SSBE from IMG.