Differential Diagnosis for a Patient with Myasthenia Gravis Presenting with Chest Pain and Shortness of Breath

Single Most Likely Diagnosis

• Myasthenic Crisis: This condition is a life-threatening complication of myasthenia gravis, characterized by severe weakness of the respiratory muscles, which can lead to respiratory failure. The patient being off their medications for a few days prior to surgery increases the risk of a myasthenic crisis, especially in the context of the physical stress of surgery.

Other Likely Diagnoses

• Pulmonary Embolism (PE): Given the recent surgery, the patient is at an increased risk for deep vein thrombosis and subsequent pulmonary embolism, which can cause chest pain and shortness of breath.
• Pneumonia: Postoperative pneumonia is a common complication, especially in patients with compromised respiratory function due to myasthenia gravis. Symptoms can include chest pain and shortness of breath.
• Atelectasis: This condition, which involves the collapse or closure of a lung resulting in reduced or absent gas exchange, can occur postoperatively, especially after surgeries that affect breathing or require prolonged periods of recumbency.

Do Not Miss Diagnoses

• Cardiac Myocardial Infarction (MI): Although less directly related to the patient's myasthenia gravis or recent surgery, myocardial infarction can cause chest pain and shortness of breath and is a critical diagnosis not to miss due to its high morbidity and mortality.
• Pneumothorax: Especially in patients with recent surgery or those with lung disease, pneumothorax can lead to sudden onset of chest pain and shortness of breath and requires immediate medical attention.

Rare Diagnoses

• Thymoma with Mediastinal Crisis: Given the patient's history of myasthenia gravis, which is often associated with thymoma, a mediastinal crisis due to a thymoma could potentially cause chest pain and shortness of breath, although this would be less common and more related to the underlying disease process rather than the immediate postoperative period.
• Respiratory Failure due to Other Causes: Other rare causes of respiratory failure, such as Guillain-Barré syndrome or acute respiratory distress syndrome (ARDS) from another cause, could also present with similar symptoms but would be less directly related to the patient's recent surgery and myasthenia gravis.