Abnormalities of swallowing mechanism, anatomical abnormalities of esophagus (webs, diverticula-pockets, strictures, masses, ulcers), hiatal hernias (outpouch of stomach above diaphragm), reflux
of stomach content into esophagus, mucosal ring (schatzki), extrinsic compression
(pressure froms tructure outside esoph).
Stomach issues like ulcers, polyps, masses, etc. Other stuff too.