A 27-year-old man presented to the emergency department with a 24-h history of dyspnea and right-sided chest pain. The pain was acute in onset, sharp in nature, worse on deep inspiration, did not radiate, and was not reproducible with palpation. There was no associated fever, cough, hemoptysis, or calf pain. The patient denied any history of recent trauma. His medical history included a left-sided acromioclavicular joint dislocation sustained in a road traffic accident that required open reduction 8 months prior to this presentation. The patient was not receiving therapy with any medications and denied smoking or illicit drug use.