<prompt> All are true about achalasia except not related -pathologyDilatation of proximal segmentIt predisposes to malignancyBody peristalsis is normalLES pressure is increased  <response>: Destruction of the nerves to LES is primary pathology and degeneration of neuromuscular function of the body of esophagus is secondary. Absence of body peristalsis and poor LES relaxation is mandatory for diagnosis. 