Student Image Challenge 01

Student Image Challenge #01

A 46 year old man presented to the gastrointestinal clinic complaining of dysphagia, regurgitation and a sensation of a lump in the throat, symptoms which have progressively worsened over the previous year. Upper GI endoscopy revealed a giant mass within the esophageal lumen, with a smooth surface covering, originated from the cervical esophagus, with a positive "squeeze sign". EUS imaging revealed a giant mobile lesion occupying the esophageal lumen.

What is the diagnosis?