Differential Diagnosis for Patient with Lung Cancer and Hemoptysis

The patient's presentation of coughing up small amounts of blood (hemoptysis) with a history of lung cancer and significantly elevated INR (16) suggests several potential diagnoses. Here's a categorized differential diagnosis:

• Single Most Likely Diagnosis

  • Bleeding due to Warfarin Therapy: The patient's significantly elevated INR (16) is a strong indicator of warfarin overdose or excessive anticoagulation, which can lead to bleeding complications, including hemoptysis. Given the patient's history of lung cancer, they may be on warfarin for thromboembolic prophylaxis or treatment, making this the most likely cause of their symptoms.

• Other Likely Diagnoses

  • Lung Cancer Progression or Metastasis: The patient's history of lung cancer and new onset of hemoptysis could indicate progression of the disease or metastasis. Lung tumors can erode into blood vessels, leading to bleeding.
  • Pulmonary Embolism or Infarction: Although less likely given the elevated INR, pulmonary embolism could still occur and cause infarction of lung tissue, leading to hemoptysis. The patient's cancer history increases their risk for thromboembolic events.
  • Infection: Pneumonia or other lung infections can cause hemoptysis, especially in immunocompromised patients such as those with cancer.

• Do Not Miss Diagnoses

  • Pulmonary Arteriovenous Malformation (AVM): Although rare, AVMs can cause significant bleeding and are more likely to be symptomatic in patients with conditions that increase right-to-left shunting or in those on anticoagulation.
  • Goodpasture Syndrome: An autoimmune disease that can cause glomerulonephritis and pulmonary hemorrhage. It's crucial to consider in patients with hemoptysis, especially if renal involvement is suspected.
  • Sepsis or Septic Emboli: In patients with lung cancer, sepsis can lead to disseminated intravascular coagulation (DIC), which might present with both bleeding and thrombosis.

• Rare Diagnoses

  • Mitral Stenosis with Pulmonary Hemorrhage: In patients with significant mitral stenosis, increased pulmonary venous pressure can lead to hemorrhage, especially if there's associated pulmonary veno-occlusive disease.
  • Idiopathic Pulmonary Hemosiderosis: A rare condition characterized by recurrent episodes of diffuse alveolar hemorrhage, often without an identifiable cause.
  • Vasculitis (e.g., Wegener's Granulomatosis): Autoimmune vasculitides can cause pulmonary hemorrhage and should be considered in the differential, especially if there are other systemic symptoms or findings suggestive of vasculitis.