Esophageal carcinoma originating in the surface epithelium with immunohistochemically proven esophageal gland duct differentiation: A case report.

A case of esophageal carcinoma exclusively composed of adenocarcinoma simulating an esophageal gland duct in a 61-year-old man is presented. The tumor arose as a slightly elevated lesion in the middle intrathoracic esophagus. It was almost completely overlaid with non-neoplastic stratified squamous epithelial cells. Beneath the overlying surface epithelium, an adenocarcinoma that was bilayered in structure diffusely invaded both the mucosal and submucosal layers. Although the tumor consisted exclusively of adenocarcinomatous cells, a keratinizing squamous cell carcinoma component was focally observed. The invasive carcinoma was focally continuous with the small area of the surface squamous epithelial layer, which was confirmed to be neoplastic by immunohistochemistry. Morphological and immunohistochemical examinations suggested that the adenocarcinomatous component arose from the esophageal surface epithelium and clearly differentiated into an esophageal gland duct. It is important to consider the possibility of this type of adenocarcinoma when diagnosing a ductal or glandular lesion of the esophagus in small biopsy specimens.