Questions 1–4 refer to the following case:

A 55-year-old Caucasian man with a history of type 2 diabetes mellitus presents to the gastroenterology clinic with a 6-month history of dysphagia. The dysphagia is worsened with solids, particularly towards the end of the day. He states that the food often gets “stuck in the middle of the chest.” The patient denies any nausea, emesis, abdominal pain, or changes in weight. There is no previous history of reflux, chest pain, dyspnea, or cough. Review of systems is otherwise benign. Physical exam is within normal limits.