A 64-year-old man develops increasing dysphagia over many months. A barium swallow is performed. What is the most likely cause of his clinical presentation?

The appearance of unexplained dysphagia in adults requires urgent evaluation. Esophageal carcinoma is particularly prevalent in certain parts of Africa and Asia, but the incidence is increasing in Western countries. In achalasia there is initially a greater tolerance for solids over liquids. In carcinoma, dysphagia for solids is noted initially, and later there is difficulty in swallowing liquids as well. Esophagoscopy is required in the workup of dysphagia. It is imperative to rule out an underlying carcinoma.