<prompt> Sudden onset of a cough followed by increasing dyspnea is characteristic ofPleural effusionLobar pneumoniaMyocardial infarctPneumothorax  <response>: PneumothoraxPatients most commonly present with chest pain, often sharp and pleuritic and may leads to severe respiratory embarrassment or becomes dull and persistent.Dyspnea is the 2ndMC symptom.Less common symptoms include a nonproductive cough and ohopnea.Physical findings may be normal if the Pneumothorax is less than 25.Characteristic physical finding includes diminished chest excursion and hyper-resonance on percussion of the affected side. Breath sounds are diminished to absent.Refer: Harrisons Principles of Internal Medicine, 18thedition, pg no: 2181, 2221, 3212 