Chapter 5, Page 7  

BARRETT'S ESOPHAGUS, COLUMNAR DYSPLASIA, AND ADENOCARCINOMA OF THE ESOPHAGUS ADENOCARCINOMA OF THE ESOPHAGUS UNASSOCIATED WITH BARRETT'S ESOPHAGUS Adenocarcinoma Arising from Heterotopic Gastric Mucosa of the Esophagus (the Inlet Patch) Heterotopic gastric mucosa of the upper esophagus is a congenital condition that results from rests of gastric precursor cells that are thought to remain after an incomplete replacement of the original esophageal mucosa by stratified squamous epithelium. A grossly visible focus of the ectopic mucosa, also known as an "inlet patch," is not uncommon and is found in 2.5 to 4 percent of patients undergoing upper endoscopy (152, 154a). Microscopic foci of gastric mucosa are thought to be even more common (156). In most instances heterotopic gastric mucosa of the esophagus is benign, but in rare cases the mucosa may undergo peptic ulceration, incomplete or complete intestinal metaplasia, or dysplasia, and carcinoma may occur (155, 156a). Although carcinoma arising from heterotopic rests in the upper esophagus is frequently mentioned in the literature, the number of actual cases reported is in the single digits (151). The tumor is seen in middle-aged patients who present with dysphagia. Endoscopy reveals a friable ulcerated tumor in the proximal esophagus. Grossly and microscopically, the tumors resemble gastric and esophageal adenocarcinomas (fig. 5-26). They commonly extend through the esophageal wall at the time of diagnosis and often metastasize to local lymph nodes. Microscopically they are adenocarcinomas with varying degrees of differentiation, and sometimes with papillary features. Ectopic gastric fundic gland mucosa must be demonstrated adjacent to the carcinoma in order to corroborate the diagnosis, although any proximal esophageal adenocarcinoma probably started in an inlet patch. Adenocarcinoma of the esophagus arising from heterotopic gastric mucosa must be distinguished from carcinoma arising from Barrett's esophagus. The latter usually occurs in the lower esophagus, and the adjacent Barrett's esophagus (which for all practical purposes never contains fundic- type mucosal glands) extends distally to the stomach. In contrast, carcinomas arising in heterotopic gastric mucosa are almost exclusively found in the upper third of the esophagus and are separated from the gastric cardia by intervening normal squamous epithelium. Rarely, adenocarcinomas can arise from esophageal mucosal and submucosal glands (see below). Unless Barrett's esophagus is excluded and an intact overlying mucosa and origin of the carcinoma from the mucosal or submucosal ducts or glands demonstrated, the diagnosis is impossible to substantiate.