PB2629: LATE DIAGNOSIS OF TWO ADULT SIBLINGS WITH BERNARD SOULIER SYNDROME (BSS)

Topic: 32. Platelet disorders Background: Bernard Soulier Syndrome (BSS) is a rare bleeding disorder with a 1 per 1 million prevalence. Most cases are diagnosed during childhood. However, like our patient, many cases are under-recognized or misdiagnosed. Aims: To raise awareness for a rare bleeding disorder that may be misdiagnosed earlier in life. Methods: We report two siblings with a delayed diagnosis of BSS. In both, we performed the following tests: complete blood count and blood smear, coagulation profile, von Willebrand antigen, von Willebrand activity, factor VIII activity, platelet aggregation test and electron microscopy examination of platelets. Results: Two siblings were diagnosed with congenital thrombocytopenia of unknown cause with a platelet count of 40×109/L to 50×109/L. Their parents had normal platelet counts without any bleeding history. The first patient is a 21-year-old female who had heavy menstrual bleeding since menarche, requiring multiple hospitalizations. The second patient is an 18-year-old male with a life-long history of easy bruising and recurrent epistaxis requiring multiple visits to the emergency department for severe nasal bleeding. In both cases, platelet aggregation tests showed a lack of agglutination with Ristocetin. Response to the other agonists was normal. Laboratory finding is shown in table 1. We decided to manage them as follows: estrogen-containing oral contraceptive pill for menorrhagia. Tranexamic acid for mucosal bleeding. Recombinant factor VIIa (90mcg/kg) in case of severe bleeding or major surgery and consideration for platelet transfusion if the above measures did not control bleeding. Summary/Conclusion: It is essential to consider BSS within the differential diagnosis of adult patients presenting with thrombocytopenia and giant platelets in the blood smear. BSS is a rare disorder that may easily have been underdiagnosed or misdiagnosed earlier in life. The presence of chronic macrothrombocytopenia in two siblings raised suspicion for an underlying genetic condition. - Test Female 21-year-old Male 18-year-old Platelet 40 ×109/L 52 ×109/L Blood smear Giant platelets Giant platelets Coagulation profile Normal Normal Factor 8 activity 1.14 U/mL 0.94 U/mL VWF antigen 0.96 U/mL 0.79 U/mL VWF Activity 1.00 U/mL 0.68 U/mL Platelet aggregation test No response to Ristocetin No response to Ristocetin Electron microscopy platelet whole mount Normal Normal Table 1 Keywords: Platelet aggregation, Bernard-Soulier syndrome

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