A 62-year-old man presents with intermittent dysphagia to solids over 6 months. Barium swallow shows a smooth, concentric narrowing at the gastroesophageal junction with a "shelf-like" appearance. The structure marked **D** in the diagram (diaphragmatic hiatus/lower esophageal sphincter at ~40 cm) is the site of this pathology. Which of the following conditions is most consistent with this radiologic finding and clinical presentation?