USMLE Step 1 Question (GI Pathology)
Pathophysiology of esophageal motility disorders
The following is a high-yield USMLE Step 1 GI question that focuses on esophageal pathology & pathophysiology.
It is followed by a deep dive into each answer choice—the answer can be found at the bottom of the post.
Good luck!
QUESTION:
A 58-year-old woman presents to the clinic with a 6-month history of progressive dysphagia, primarily with solid foods, and unintentional weight loss of 10 pounds. She also reports frequent regurgitation of undigested food particles and occasional nocturnal cough. Her temperature is 98.2°F (36.8°C), heart rate is 80/minute, respiratory rate is 16/minute, and blood pressure is 130/85 mmHg. Physical examination is unremarkable, and laboratory studies show no significant abnormalities. A barium swallow study reveals a dilated, tapered esophagus at the gastroesophageal junction. Based on the clinical findings, which of the following is the most likely diagnosis?
A) Zenker's diverticulum with associated esophageal dysmotility
B) Peptic stricture secondary to gastroesophageal reflux disease
C) Gastroesophageal reflux disease with atypical presentation
D) Scleroderma-associated esophageal dysmotility with distal esophageal narrowing
E) Diffuse esophageal spasm with impaired lower esophageal sphincter function
F) Primary esophageal motility disorder with impaired lower esophageal sphincter relaxation
G) Eosinophilic esophagitis with concurrent esophageal dysmotility
Want the answer now? Scroll to the bottom of the page.
Want to learn how to tackle this type of question? Read the DEEP-DIVE below.
DEEP-DIVE:
The patient presents with progressive dysphagia to solids, regurgitation of undigested food, and nocturnal cough.
These findings suggest an esophageal disorder.
The barium swallow, showing a dilated esophagus with tapering at the gastroesophageal junction, suggests a motility disorder affecting the lower esophageal sphincter (LES).
THE THOUGHT PROCESS TO ANSWERING THIS QUESTION:
What are they asking us to do? Make a diagnosis (This will most likely be an ‘indirect’ first-order question). This means that you’ll likely need to identify the diagnosis and choose an answer that best describes it—it is rare to have a direct first-order diagnosis question on the USMLE exams.
What you have to do here:
1st. Identify the most likely diagnosis based on the given signs & symptoms
2nd. Check the answer choices and select the option that best matches the diagnosis
A. Zenker's diverticulum with associated esophageal dysmotility
Zenker's diverticulum is an outpouching of the esophageal mucosa in the pharyngoesophageal region, just above the upper esophageal sphincter. It can cause dysphagia, regurgitation, and halitosis. However, it typically presents with dysphagia to both solids and liquids.
The barium swallow study would reveal a diverticulum in the proximal esophagus, not a dilated, tapered esophagus at the gastroesophageal junction.
B. Peptic stricture secondary to gastroesophageal reflux disease
Peptic strictures are a complication of chronic gastroesophageal reflux disease (GERD) and can cause progressive dysphagia, primarily to solids.
The barium swallow study in peptic strictures would show a focal narrowing of the esophagus, typically in the distal esophagus, rather than a dilated, tapered appearance.
C. Gastroesophageal reflux disease with atypical presentation
GERD can cause a variety of symptoms, including dysphagia, regurgitation, and nocturnal cough. However, a dilated, tapered esophagus at the gastroesophageal junction is not a typical finding in GERD.
GERD is more likely to cause esophageal inflammation (esophagitis) or peptic strictures, which would appear as narrowing on a barium swallow study.
D. Scleroderma-associated esophageal dysmotility with distal esophageal narrowing
Scleroderma is an autoimmune disorder that can cause esophageal dysmotility and lead to symptoms similar to those described in the question.
However, scleroderma typically presents with other systemic symptoms, such as skin tightening, Raynaud's phenomenon, and telangiectasias. Without these additional findings, scleroderma is a less likely diagnosis.
E. Diffuse esophageal spasm with impaired lower esophageal sphincter function
Diffuse esophageal spasm is a motility disorder characterized by uncoordinated contractions of the esophagus. It can cause dysphagia and regurgitation but typically presents with intermittent symptoms and chest pain.
The barium swallow study in diffuse esophageal spasm may show segmental contractions and a "corkscrew" appearance but not a consistently dilated esophagus with distal narrowing.
F. Primary esophageal motility disorder with impaired lower esophageal sphincter relaxation
Primary esophageal motility disorders, such as achalasia, are characterized by impaired lower esophageal sphincter relaxation and loss of peristalsis in the esophageal body. This leads to progressive dysphagia, regurgitation of undigested food, weight loss, and occasional nocturnal cough due to aspiration.
The barium swallow study in achalasia classically reveals a dilated esophagus with distal narrowing ("bird's beak" appearance) at the gastroesophageal junction.
G. Eosinophilic esophagitis with concurrent esophageal dysmotility
Eosinophilic esophagitis is an immune-mediated disorder characterized by eosinophilic infiltration of the esophageal mucosa. It can cause dysphagia, food impaction, and chest pain but is more common in younger individuals and often presents with a history of atopy (e.g., asthma, allergic rhinitis).
The barium swallow study in eosinophilic esophagitis may show esophageal narrowing, rings, or furrows. A dilated esophagus with distal tapering is unlikely.
VERDICT: Based on the patient's presentation and barium swallow findings, the most likely diagnosis is a primary esophageal motility disorder with impaired lower esophageal sphincter relaxation, specifically achalasia (answer choice F). The presence of progressive dysphagia, regurgitation, weight loss, and dilated esophagus with distal narrowing are all consistent with this diagnosis.
FINAL ANSWER: F. Primary esophageal motility disorder with impaired lower esophageal sphincter relaxation
