PLE-1950

A 71-year-old male patient complained of swallowing difficulty after ingesting meat two days ago. An endoscopy was performed, and a meat bolus was found 30 cm from the incisors. The bolus was removed, revealing a lower esophageal ring at the esophagogastric junction. Biopsy results showed normal esophageal squamous epithelium on one side and gastric columnar epithelium on the distal side of the membrane. What is the probable diagnosis?