esophageal ring

DEFINITION: A circumferential, thin, web-like narrowing in the lower esophagus. Rings are distinct from webs, which are eccentric/membranous and typically occur in the upper esophagus.

TYPES: - A-ring (muscular ring): Located proximal to the gastroesophageal junction, at the upper end of the lower esophageal sphincter vestibule. It is covered by squamous mucosa and contains muscle. It is rare, thick, and often asymptomatic. - B-ring (Schatzki ring, mucosal ring): Located at the squamocolumnar (Z-line) junction. Squamous mucosa lines the upper surface and columnar (gastric) mucosa lines the lower surface. It is thin (2-4 mm), it is the most common type, and it is nearly always associated with a sliding hiatal hernia. It is visible only when the esophagus is well distended, so it is best seen on barium swallow.

PATHOPHYSIOLOGY: The cause is uncertain. Proposed contributors include GERD/chronic inflammation and fibrosis, and a congenital or acquired mucosal fold at the GE junction. Eosinophilic esophagitis is also associated with rings, though those are typically multiple ("feline/ringed esophagus") and in the mid-to-distal esophagus.

CLINICAL FEATURES: - Symptoms usually appear when the lumen is <13 mm. Rings wider than 20 mm are usually asymptomatic. - Intermittent, nonprogressive dysphagia to SOLIDS only (not liquids), often with a bolus such as meat. This is "steakhouse syndrome" or food impaction. - Often an incidental finding. - Contrast with: achalasia (dysphagia to both solids and liquids from the start), peptic stricture or esophageal cancer (progressive dysphagia, solids then liquids), and esophageal spasm (intermittent, both solids and liquids, chest pain).

DIAGNOSIS: Barium esophagram (a thin ring at the GE junction with a hiatal hernia) or upper endoscopy (EGD). EGD is needed to exclude other causes such as eosinophilic esophagitis, and it allows treatment.

TREATMENT: - Dietary modification: chew food thoroughly, eat slowly. - Symptomatic rings: endoscopic bougie or balloon dilation, which disrupts the ring. - Recurrence: consider PPI therapy for GERD, repeat dilation, or endoscopic incision or biopsy-based disruption.

BOARD PEARLS: - Schatzki ring = lower esophageal mucosal B-ring + hiatal hernia + intermittent solid-food dysphagia. - Plummer-Vinson syndrome = upper esophageal web + iron deficiency anemia + dysphagia in middle-aged women, with a risk of squamous cell carcinoma. This is the classic distractor. - Intermittent dysphagia to solids points to a ring or web. Progressive dysphagia points to a stricture or malignancy.