although roentgenographic studies may show a mild-esophageal stricture or an esophageal ulcer , definitive diagnosis requires endoscopy with directed biopsy of erythematous mucosa in the esophagus , or manometrically guided biopsies for showing the presence of columnar epithelium above the lower esophageal sphincter .
C0014876
esophagus
C0227192
lower esophageal sphincter