A 67-year-old woman with a 6-year history of myasthenia gravis presents with worsening exertional dyspnea. Past medical history includes coronary artery disease (stent placement), diabetes, and intermittent shortness of breath with previous oxygen dependence due to MG. Family history is notable for a sister who died from myasthenia gravis complications. She has a 60 pack-year smoking history, quit 10 years ago. Diagnostic findings include a chest radiograph showing a lobulated anterior mediastinal mass with mild elevation of the left hemidiaphragm (suggestive of phrenic nerve involvement) and a CT chest revealing an 8-cm left-sided anterior mediastinal mass with a 1-cm left pleural nodule consistent with drop metastasis.
