Differential Diagnosis for Hemoptysis with Low Platelet Count

• Single most likely diagnosis
  • Thrombocytopenia due to bone marrow suppression or bleeding disorder: This is a likely cause because a low platelet count can lead to bleeding in various parts of the body, including the lungs, resulting in hemoptysis.
• Other Likely diagnoses
  • Pulmonary embolism with infarction: This condition can cause hemoptysis, and a low platelet count can increase the risk of bleeding.
  • Infections such as pneumonia or tuberculosis: Certain infections can cause both hemoptysis and thrombocytopenia.
  • Malignancy (lung cancer or metastatic disease): Cancer can cause hemoptysis and may also lead to thrombocytopenia due to bone marrow involvement or paraneoplastic syndromes.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed)
  • Pulmonary arteriovenous malformation (AVM): Although rare, AVMs can cause life-threatening hemoptysis, and a low platelet count can exacerbate bleeding.
  • Goodpasture syndrome: This autoimmune disease can cause hemoptysis and renal failure, and it is essential to diagnose and treat promptly.
  • Sickle cell disease with pulmonary involvement: Sickle cell disease can cause hemoptysis and has associated thrombocytopenia.
• Rare diagnoses
  • Idiopathic thrombocytopenic purpura (ITP) with pulmonary hemorrhage: Although ITP primarily causes mucocutaneous bleeding, it can rarely cause pulmonary hemorrhage.
  • Lymphangioleiomyomatosis (LAM): This rare lung disease can cause hemoptysis, and some patients may have associated thrombocytopenia.
  • Mitral stenosis with pulmonary hemorrhage: This condition can cause hemoptysis, especially if there is associated pulmonary hypertension or thrombocytopenia.