<prompt> All are true about achalasia exceptDilatation 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 the esophagus is secondary. An absence of body peristalsis and poor LES relaxation is mandatory for diagnosisRef: Harrison; 19th edition 