Thin (2-3mm) membranes of normal esophageal tissue consisting of mucosa and submucosa that can be congenital or acquired. Congenital webs commonly appear in the middle and inferior third of the esophagus, and they are more likely to be circumferential with a central or eccentric orifice. Acquired webs are much more common than congenital webs and typically appear in the cervical area (postcricoid). Clinical symptoms of this condition are selective (solid more than liquids) dysphagia, thoracic pain, nasopharyngeal reflux, aspiration, perforation and food impaction (the last two are very rare). [from
HPO]