A 72-year-old woman with an unremarkable medical history underwent an upper gastrointestinal endoscopy in May 2002 because of dyspepsia. An examination showed a pedunculated polyp lesion in an inlet patch on the posterior wall of the esophagus, 20 cm distant from the incisors and measuring 1.5 cm. Forceps biopsies were obtained, and the pathological analysis showed a gastric-like mucosa with well-differentiated pyloric glands below an atrophic squamous epithelium; most of the glands were lined with atypical cells, compatible with low-grade dysplasia. Histological examination after endoscopic removal showed a low-grade dysplasia in an adenomatous polyp of the esophagus developing on pyloric-type heterotopic gastric mucosa (HGM). Three years later, the patient remains well with no evidence of esophageal disease. We review 25 reported cases of adenocarcinoma and 3 cases of high-grade dysplasia arising in HGM.