A 50-year-old school bus driver complainedof long-standing heartburn occasionally associated withregurgitation of the food into the mouth. He smokes twopacks of cigarettes a day, likes to eat spicy food, and onweekends drinks a case of beer. He was given antacids andwas told to lose weight, stop smoking, and change hisdrinking and eating habits. For the last 3 months he has haddifficulties swallowing solid food. Since the heartburn didnot respond to antacids he was scheduled for an uppergastrointestinal (UGI) endoscopy. Physical findings The patient is obese, but otherwise in relatively good health.Laboratory findings No abnormalities were detected.Diagnostic procedures A UGI endoscopy revealed that the normal esophageal mucosa has been replaced by velvety red patches and streaks extending 5 cm above the gastroesophageal junction.A biopsy was performed on this part of the esophagus, and the diagnosis of Barrett’s esophagus without signs of epithelial atypia or dysplasia was made. Questions for you to answer: 1. What is the most likely cause of heartburn in this patient? 2. Explain the pathogenesis of heartburn in general. 3. How is obesity related to heartburn? What other risk factors for heartburn can you identifyin his history? 4. Does this patient have dysphagia or odynophagia? How does the difficulty swallowing hard food differ from difficulty in swallowing liquids? 5. What could one expect to find by endoscopy in this patient? 6. Describe the histopathologic findings in Barrett’s esophagus. Why is it important to know whether epithelial dysplasia is present in a case of Barrett’s esophagus?