Differential Diagnosis for a 51-year-old Female with Left-Sided Pain and Dyspnea

Single Most Likely Diagnosis

• Pulmonary Embolism (PE): Given the patient's history of cancer, recent port placement, and symptoms of dyspnea and pain that worsens with coughing, PE is a highly plausible diagnosis. The patient's smoking history and potential for immobility due to chemotherapy also increase the risk.

Other Likely Diagnoses

• Pneumonia: The patient's symptoms of dyspnea, pain exacerbated by coughing, and a history of smoking make pneumonia a possible diagnosis. The absence of fever or nausea does not rule out pneumonia.
• Pleurisy: The sharp pain that worsens with coughing could indicate pleurisy, which can be associated with pneumonia, pulmonary embolism, or as a standalone condition.
• Musculoskeletal Pain: Given the initial back pain that migrated to the left side, musculoskeletal pain, possibly related to muscle strain or costochondritis, is a consideration, especially if the patient has been less active due to chemotherapy.

Do Not Miss Diagnoses

• Aortic Dissection: Although less likely given the lack of chest pain and no recent surgery or trauma, aortic dissection is a critical diagnosis to consider due to the patient's family history of aneurysms. The initial back pain could be a red flag for this condition.
• Pneumothorax: The sudden onset of dyspnea and pain, especially if exacerbated by coughing, necessitates consideration of pneumothorax, which could be spontaneous or related to the port placement.
• Pericarditis: This condition can cause chest pain that may radiate to the back and is exacerbated by coughing or deep breathing. Although less common, it's a critical diagnosis not to miss due to its potential complications.

Rare Diagnoses

• Lung Cancer: Although the patient has a history of cancer, a new primary lung cancer or metastasis could present with these symptoms, especially in a smoker.
• Empyema or Pleural Effusion: These conditions could result from pneumonia, cancer, or other infections and would explain the patient's symptoms, especially if there's a significant collection of fluid in the pleural space.
• Rib Fracture: Less likely without a history of trauma, but possible if the patient experienced an unwitnessed or unreported event, or if there was a pathologic fracture due to metastatic disease.