A 58-year-old man presents with a 6-month history of intermittent dysphagia to solids, particularly meat and bread, with no difficulty swallowing liquids. He denies weight loss. Upper endoscopy reveals a thin, symmetric, circumferential mucosal narrowing at the gastroesophageal junction (marked **D** in the diagram). Biopsies from the mid and distal esophagus show normal histology. Which of the following best describes the pathophysiology of the structure marked **D**?

Explanation

## Why "Chronic gastroesophageal reflux disease causing mucosal scarring and fibrosis at the squamocolumnar junction" is right The structure marked **D** is a Schatzki B-ring — a thin, mucosal, concentric narrowing at the squamocolumnar junction. The clinical anchor is that Schatzki rings are **strongly associated with GERD and hiatal hernia**, and chronic acid exposure causes mucosal scarring and fibrosis at the squamocolumnar junction, producing the ring. This patient's presentation—intermittent solid-food dysphagia with normal liquid swallowing, no weight loss, and a thin symmetric mucosal ring on endoscopy—is pathognomonic for Schatzki B-ring. Normal biopsies exclude eosinophilic esophagitis. (Sleisenger & Fordtran 11e Ch 43; Harrison 21e Ch 322) ## Why each distractor is wrong - **Congenital muscular hypertrophy of the lower esophageal sphincter with progressive dysmotility**: This describes achalasia or diffuse esophageal spasm, not a thin mucosal ring. Schatzki rings are mucosal (not muscular) and are acquired, not congenital. Dysmotility is not the mechanism. - **Eosinophilic infiltration of the esophageal mucosa with subepithelial fibrosis**: This describes eosinophilic esophagitis (EoE), which can mimic Schatzki ring clinically but is excluded here by normal biopsies (EoE requires >15 eosinophils/HPF). EoE typically presents with multiple rings/"trachealization" and is more common in young men with atopy. - **Malignant transformation of Barrett metaplasia with early adenocarcinoma**: Esophageal carcinoma presents with progressive dysphagia (not intermittent), weight loss, and an asymmetric mass on endoscopy. This patient has no weight loss and a symmetric ring—classic for benign Schatzki, not malignancy. **High-Yield:** Schatzki B-ring = intermittent solid-food dysphagia + thin symmetric mucosal ring at Z-line + GERD/hiatal hernia = treat with dilation + lifelong PPI. [cite: Sleisenger & Fordtran 11e Ch 43; Harrison 21e Ch 322]