Adenocarcinoma complicating Barrett's esophagus: an analysis of cell proliferation.

In Japan, cases of Barrett's esophagus with concurrent adenocarcinoma are relatively rare. We report herein a case of long-segment Barrett's esophagus-associated adenocarcinoma in a 72-year-old Japanese man. The surgical specimen showed that an ulcerating tumor, measuring 5.5 x 3.9 cm, was present in the lower esophagus adjacent to the esophagogastric junction, the background lower esophagus having an erythematous appearance. Histologically, the ulcerating tumor was a well-to-moderately differentiated tubular adenocarcinoma, with a small area of signet ring cell carcinoma invading the adventitia. In addition, the esophageal epithelium was replaced by columnar epithelium (9.5 cm in length) with multifocal dysplastic changes. Immunohistochemically, the number of Ki-67-positive cells gradually increased, moving from the normal gastric mucosa (mean Ki-67 labeling index [mKLI], 2.6%) through Barrett's epithelium (mKLI, 12.9%), low-grade dysplasia (mKLI, 16.9%), and high-grade dysplasia (mKLI. 23.7%) to invasive carcinoma, in that order, with labeling higher in the invasive tubular adenocarcinoma elements (mKLI, 40.5%) than in areas of signet ring cell carcinoma (mKLI, 20.4%). Findings in our patient suggest that increased cellular proliferation plays an integral part, in the progression of Barrett's metaplasia to adenocarcinoma. The collection of further cases for analysis will be necessary to confirm this hypothesis.