<prompt> All are precancerous lesions for carcinoma of esophagus exceptAchalasiaPaterson Kelly syndromeZenker DiveiculumEctodermal dysplasia  <response>: Refer Robbins page no Pg 758-9 A Zenkers diveiculum, more formally known as a hypopharyngeal diveiculum, is a pouch that can form at the junction of the hypopharynx lower pa of the throat and the esophagus, an area known as Killians Triangle 