Plummer-Vinson syndrome

A 42-year-old woman who recently emigrated from Norway comes to the free clinic because of progressive trouble swallowing for the past few months. She says that when she tries to swallow bread, it often feels like it gets stuck before it reaches her stomach. She also complaints of fatigue and shortness of breath after walking up the stairs to her 2nd-floor apartment that requires her to rest for several minutes to recover. Her current medications include an oral contraceptive pill. Her temperature is 37.0°C (98.6°F), pulse is 88/min, respirations are 17/min, and blood pressure is 110/66 mm Hg. Physical examination shows a thin, pale woman with a smooth, red, and shiny tongue. Laboratory studies show a hemoglobin of 9.1g/dL and a leukocyte count of 9,000mm³. Barium esophagram shows multiple esophageal webs, as shown below. Which of the following is the most likely diagnosis?