Differential Diagnosis

The patient presents with progressive pain in her left shoulder and upper arm after physical exertion, which could be indicative of several conditions. Here's a categorized differential diagnosis:

• Single most likely diagnosis

  • Musculoskeletal strain or impingement syndrome of the left shoulder: The patient's symptoms started after moving heavy boxes, which suggests a mechanical or overuse injury to the shoulder. The pain's location and the fact that it worsened with activity (carrying empty boxes upstairs) support this diagnosis.

• Other Likely diagnoses

  • Cervical radiculopathy: Although less likely given the direct correlation with physical exertion and the specific location of pain, cervical radiculopathy could cause shoulder and arm pain. However, the absence of neurological deficits on examination makes this less probable.
  • Pulmonary embolism (considered under pulmonary issues): While the patient has risk factors for thromboembolic disease (smoking history), the presentation is not typical for a pulmonary embolism, which usually includes more pronounced respiratory symptoms and possibly signs of right heart strain.

• Do Not Miss (ddxs that may not be likely, but would be deadly if missed)

  • Myocardial infarction: Although the electrocardiogram is unremarkable, cardiac causes of chest and arm pain must always be considered, especially in a patient with risk factors like smoking and hypertension. The presence of nausea and the fact that pain occurred at rest (this morning) could suggest cardiac ischemia.
  • Pulmonary embolism: As mentioned, while less likely, the potential consequences of missing this diagnosis are severe, and any patient with risk factors and acute onset of pain should be evaluated for this condition.
  • Aortic dissection: This is a less common but critical diagnosis to consider in patients with severe, acute pain, especially if the pain is tearing in nature and radiates to the back. The patient's hypertension increases the risk for this condition.

• Rare diagnoses

  • Thoracic outlet syndrome: This condition involves compression of the nerves and/or blood vessels that pass into the thoracic outlet (the space between your collarbone and first rib). It could cause shoulder and arm pain but is less common and typically associated with specific maneuvers that reproduce the symptoms.
  • Pancoast tumor: A rare type of lung cancer that can cause shoulder and arm pain due to invasion of the brachial plexus. Given the patient's smoking history, this could be considered, but it would be an uncommon presentation without other symptoms like weight loss or more pronounced respiratory symptoms.