Differentials
Mild haemophilia A
SIGNS / SYMPTOMS
Bleeding symptoms may be similar to von Willebrand disease (VWD; particularly type 2 and 3 VWD), although patients with VWD tend to have more mucosal bleeding symptoms.
Mainly occurs in boys and men due to X-linked pattern of inheritance. A positive family history may be absent because haemophilia A can result from spontaneous germline mutations and/or somatic mosaicism during early embryogenesis.[56]
INVESTIGATIONS
Patients with haemophilia A normal von Willebrand factor (VWF) levels, but decreased factor VIII (FVIII) levels.
Genetic testing is positive for genetic mutations associated with haemophilia.
VWF FVIII binding assay (VWF:FVIIIB) and genetic testing can distinguish type 2N VWD from haemophilia A.[15]
Inherited platelet function disorder
SIGNS / SYMPTOMS
No differentiating signs/symptoms.
Rare severe platelet function disorders such as Glanzmann's thrombasthenia and Bernard-Soulier syndrome are autosomal recessive in inheritance, but most inherited platelet function disorders are autosomal dominant.
INVESTIGATIONS
Patients with inherited platelet function disorders have abnormal platelet aggregometry but normal VWF levels.
Acquired von Willebrand syndrome
SIGNS / SYMPTOMS
Bleeding symptoms to von Willebrand disease (VWD), but a personal and family history of bleeding consistent with VWD will be absent.[20][57] Patients will often have a personal or family history of an autoimmune, lymphoproliferative, myeloproliferative, or cardiovascular disorder.[57]
INVESTIGATIONS
Laboratory findings may be similar.
Additional tests may be required to identify an underlying disorder associated with AVWS (if unknown).[2][58][59] For example, CBC may show elevated platelet count in AVWS associated with essential thrombocythemia. Thyroid function may be positive for hypothyroidism; serum protein electrophoresis may be positive for monoclonal gammopathies; and transthoracic echocardiogram may be positive for aortic stenosis.[58]
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