Differential Diagnosis for a 65-year-old patient with von Willebrand's antigen of 1.33 and von Willebrand's factor activity of 0.93

• Single most likely diagnosis:
  • Normal variant or mild von Willebrand disease (Type 1): The patient's von Willebrand factor activity is slightly below the normal range, but the antigen level is also low, which could suggest a mild form of Type 1 von Willebrand disease. However, these levels can also be seen in normal individuals, especially considering the wide range of normal values for these tests.
• Other Likely diagnoses:
  • Type 1 von Willebrand disease: As mentioned, the patient's levels are on the border of what is considered normal, making Type 1 von Willebrand disease a possible diagnosis, especially if the patient has a personal or family history of bleeding symptoms.
  • Acquired von Willebrand syndrome: This condition can mimic von Willebrand disease but is caused by an underlying condition such as cardiovascular disease, lymphoproliferative disorders, or the use of certain medications. The patient's age and potential for underlying health issues make this a consideration.
• Do Not Miss diagnoses:
  • Severe von Willebrand disease (Type 3): Although less likely given the patient's factor activity and antigen levels, severe forms of the disease can present with variable levels due to the consumption of von Willebrand factor during bleeding episodes. Missing this diagnosis could lead to inadequate treatment during surgical procedures or significant bleeding events.
  • Other bleeding disorders: Conditions like hemophilia A or B, or other platelet function disorders, could present with similar bleeding symptoms and should not be overlooked, especially if the patient reports significant bleeding episodes.
• Rare diagnoses:
  • Type 2B von Willebrand disease: This subtype is characterized by an increased affinity of von Willebrand factor for platelets, leading to thrombocytopenia. The patient's laboratory values do not strongly support this diagnosis, as Type 2B typically presents with a disproportionate decrease in von Willebrand factor activity compared to antigen level, and often with thrombocytopenia.
  • Type 2A or 2M von Willebrand disease: These subtypes involve qualitative defects in von Willebrand factor. While possible, they are less likely given the patient's presentation and the fact that these subtypes usually have more significantly impaired von Willebrand factor activity relative to antigen levels.