Organ System Pathology USMLE Step 1 Practice Question
A 41-year-old woman presents with several months of progressive dysphagia to both solids and liquids. She also reports regurgitation of undigested food and a 4-kg weight loss. Physical examination is unremarkable. A barium swallow shows a dilated esophagus with smooth tapering at the distal end. Which of the following best explains the pathogenesis of this disorder?
Answer choices
- ALoss of myenteric inhibitory neurons containing nitric oxide and vasoactive intestinal peptideCorrect answer
- BHypertrophy of the pyloric circular muscle
- CAutoimmune destruction of parietal cells with loss of intrinsic factor
- DLongitudinal mucosal lacerations at the gastroesophageal junction
- EMetaplastic transformation of distal squamous epithelium into columnar epithelium
- FSecondary achalasia from Trypanosoma cruzi myenteric plexus destruction in Chagas disease
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