Traditional serrated adenoma in a patient with Barrett's esophagus.

Background: Protruding adenomas in the Barrett's mucosa (BM) are very rare. Out of the 22 adenomas evolving in BM recorded in the literature, 21 were tubular and the remaining one, villous.

Case Report: We describe a case of traditional serrated adenoma (TSA) in BM. The TSA displayed hyperplastic fronds with saw-like indentations lined with low-grade dysplasia. In addition, dysplastic cells and atypical mitoses reaching the luminal epithelial border (high-grade dysplasia) were observed in the lower part of the TSA. Cell proliferation (Ki67) mostly occurred at the bottom of the dysplastic serrations. In non-dysplastic subjacent glands with intestinal metaplasia, goblet cells contained sialomucins (alcian blue pH 2.5) and mucopolysaccharides (periodic acid Schiff). The TSA was found at the border of an invasive adenocarcinoma.

Conclusion: The review of the literature indicates that this is first case of TSA in the BM ever reported. It remains unclear as to whether the TSA was an independent non-invasive neoplastic bystander, or an integral pre-cancerous remnant of the adenocarcinoma domain.