Smooth, circumferential ring of squamous mucosa, often responsible for causing difficulty swallowing (dysphagia), which can be located any where along the esophagus, or which may be asymptomatic. Left: Symptomatic cervical esophageal web found in the cervical esophagus in a 71 year-old man. Center: Asymptomatic ring incidentally found in the proximal esophagus of a 40 year-old man. Right: Asymptomatic, nonobstructing partial web found in the midesophagus of a 74 year-old woman.