Case Presentation: A 45-year-old woman with a history of ER-/PR-/Her2+ breast cancer previously in remission, recently diagnosed with recurrent metastatic breast cancer pathologically and on imaging, presented to the hospital with multiple days of dyspnea and dry cough. Vitals were remarkable for hypoxia and tachycardia. Electrocardiogram showed sinus tachycardia without ischemic changes. Troponin and B-type [...]