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Difficulty: MediumFormulating a Differential Diagnosis

A 2626-year-old woman is evaluated in the hematology clinic for a history of easy bruising, frequent epistaxis, and heavy menstrual bleeding since menarche. She reports that a recent tooth extraction resulted in oozing that lasted for 22 days. She has no history of joint swelling or deep muscle pain. She takes no medications and does not use tobacco, alcohol, or illicit drugs. Vital signs are within normal limits. Physical examination shows several small ecchymoses on the upper and lower extremities but no petechiae, jaundice, or hepatosplenomegaly.

Laboratory studies show:
Hemoglobin: 11.4 g/dL11.4 \text{ g/dL}
Mean corpuscular volume: 78 fL78 \text{ fL}
Platelet count: 260,000/mm3260,000/\text{mm}^3
Prothrombin time (PT): 11 seconds11 \text{ seconds}
Activated partial thromboplastin time (aPTT): 46 seconds46 \text{ seconds} (normal: 25−35 seconds25-35 \text{ seconds})

A mixing study with normal plasma completely corrects the aPTT to 30 seconds30 \text{ seconds}.

Based on the clinical presentation and laboratory findings, which of the following is the most likely diagnosis?

  1. von Willebrand diseaseAnswer
  2. B
    Antiphospholipid syndrome
  3. C
    Factor VII deficiency
  4. D
    Hemophilia A
  5. E
    Immune thrombocytopenic purpura

Answer

von Willebrand disease
The correct diagnosis is von Willebrand disease (vWD), the most common inherited bleeding disorder. This patient's presentation of epistaxis, easy bruising, and menorrhagia (with secondary iron deficiency anemia) strongly points to a defect in primary hemostasis. The laboratory evaluation shows an isolated prolonged aPTT that completely corrects with a mixing study, indicating a factor deficiency in the intrinsic coagulation pathway. This dual clinical-laboratory picture is the hallmark of vWD. von Willebrand factor (vWF) is necessary for platelet adhesion to damaged endothelium. Furthermore, vWF serves as a protective carrier protein for Factor VIII in the plasma. A significant reduction in vWF leads to the rapid clearance and degradation of Factor VIII, thereby prolonging the aPTT. The normal platelet count rules out primary thrombocytopenic conditions, and the bleeding pattern effectively rules out classic hemophilias.

Step-by-Step Solution

1
Analyze the clinical phenotype.
The patient has a history of epistaxis, bruising, and heavy menses without hemarthrosis.
This specific pattern indicates a defect in primary hemostasis (platelet plug formation) rather than deep tissue bleeding seen in secondary hemostasis defects.
2
Evaluate the coagulation profile.
Platelets and PT are normal. The aPTT is prolonged but corrects with a mixing study.
A correcting prolonged aPTT indicates a deficiency of a clotting factor in the intrinsic or common pathway, ruling out an inhibitor like lupus anticoagulant.
3
Synthesize the clinical and laboratory findings to formulate the diagnosis.
The combination of mucocutaneous bleeding and an intrinsic pathway factor deficiency points to von Willebrand disease.
von Willebrand factor mediates platelet adhesion (primary hemostasis) and acts as a carrier protein for Factor VIII. Its deficiency leads to both mucocutaneous bleeding and rapid degradation of Factor VIII, thus prolonging the aPTT.

Key Concept

Formulating a differential diagnosis for bleeding disorders by integrating clinical bleeding patterns (mucocutaneous vs. deep tissue) with coagulation cascade laboratory results (PT, aPTT, and mixing studies).
Estimated Time:1m 30s
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Formulating a Differential Diagnosis

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