Differential Diagnosis for Patient with Epistaxis and Bruising

Single Most Likely Diagnosis

• Thrombotic Thrombocytopenic Purpura (TTP): The patient's presentation with epistaxis, bruising, a rapid decline in platelet count, elevated LDH, and low haptoglobin is highly suggestive of TTP. The condition is characterized by the formation of blood clots in small blood vessels throughout the body, which can lead to a low platelet count, microangiopathic hemolytic anemia (evidenced by elevated LDH and low haptoglobin), and organ dysfunction.

Other Likely Diagnoses

• Immune Thrombocytopenic Purpura (ITP): Although ITP typically presents with isolated thrombocytopenia and a more gradual decline in platelet count, the patient's symptoms of epistaxis and bruising could be consistent with this diagnosis. However, the rapid decline in platelet count and the presence of elevated LDH and low haptoglobin make TTP more likely.
• Disseminated Intravascular Coagulation (DIC): DIC can present with thrombocytopenia, elevated LDH, and low haptoglobin, but it is typically associated with a more complex clinical picture, including evidence of coagulopathy (e.g., prolonged PT/INR, low fibrinogen), which is not mentioned in the scenario.

Do Not Miss Diagnoses

• Hemolytic Uremic Syndrome (HUS): Similar to TTP, HUS is characterized by microangiopathic hemolytic anemia, thrombocytopenia, and renal failure. Although the patient's presentation is more suggestive of TTP, HUS should be considered, especially if there is any evidence of renal dysfunction.
• Severe Sepsis or Septic Shock: Although the patient is not currently bleeding and the WBC is normal, severe sepsis or septic shock can cause thrombocytopenia, elevated LDH, and low haptoglobin due to disseminated intravascular coagulation. It is crucial to consider this diagnosis, as it requires immediate and aggressive treatment.

Rare Diagnoses

• Atypical Hemolytic Uremic Syndrome (aHUS): A rare disorder characterized by microangiopathic hemolytic anemia, thrombocytopenia, and renal failure, often without a clear precipitating factor. It is less likely than TTP or HUS but should be considered if other diagnoses are ruled out.
• Paroxysmal Nocturnal Hemoglobinuria (PNH): A rare, acquired, life-threatening disease of the blood characterized by the destruction of red blood cells, bone marrow failure, and the potential for thrombotic events. Although it could explain some of the patient's laboratory findings, it is less likely given the acute presentation and rapid decline in platelet count.