Aim of the work The objective of this study was to identify the most common esophageal lesion among all archival biopsies received in the pathology departments of both faculty of medicine (Cairo University) and Theodor Bilharz Research Institute, Egypt, over 5 years (2004)(2005)(2006)(2007)(2008). The pathologic features of all studied cases were studied. Additional work undertaken included immunohistochemical study of one of the most common proliferative markers, Ki-67 (MIB1), in cases of gastroeosophageal reflux disease (GERD), Barrett's esophagus, and esophageal carcinoma. Materials and methodsThe study included 210 archival esophageal biopsies, all of which were recut from paraffin blocks and stained with hematoxylin and eosin. Patient consent was not taken because of difficulty in contacting them. Cases of GERD, Barrett's esophagus, esophageal squamous cell carcinoma (SqCC), and esophageal adenocarcinoma were evaluated with respect to their proliferative activity using Ki-67 immunohistochemistry. ResultsOf the 210 eosophageal specimens, 54.76% were GERD, 17.61% were Barrett's esophagus, 3.81% were benign lesions, 18.6% were malignant lesions (10.48% SqCC, 6.19% adenocarcinoma, and 1.9% undifferentiated carcinoma), and 5.24% represented others. There were no statistically significant differences with respect to age among the 210 eosophageal specimens. Patients with cancer were predominantly men. The Ki-67 index averaged 9.4 ( ± 3.7)% in GERD specimens (n = 115), 23.6 ( ± 7.0)% in Barrett's esophagus (n = 37), 35.4 ( ± 10)% in adenocarcinoma specimens (n = 13), and 41.5 ( ± 9.9)% in SqCC specimens (n = 22). Ki-67 expression was significantly different between the groups. There was a strong linear correlation between Ki-67 expression and the GERD-Barrett's-adenocarcinoma sequence.Conclusion GERD is the most common pathological lesion encountered in Egypt. The Ki-67 antigen has increased expression along the GERD-metaplasiaadenocarcinoma sequence. There is a strong linear correlation between Ki-67 proliferative activity and Barrett's carcinogenesis. There is also a strong linear correlation between Ki-67 proliferative activity and SqCC of the esophagus.