Which condition is most likely associated with giant platelets on a peripheral smear?

Which condition is most likely associated with giant platelets on a peripheral smear?

• A. Bernard-Soulier
• B. Wiskott-Aldrich
• C. Hermansky-Pudlak
• D. Glanzmann

Answer: (A)

Giant platelets on a smear point to macrothrombocytopenia caused by a platelet adhesion defect, most classically Bernard-Soulier syndrome. This disorder stems from a defective GPIb-IX-V receptor complex that binds von Willebrand factor, so platelets don’t adhere properly to damaged vessels. The consequence is impaired platelet production leading to unusually large platelets being released by the megakaryocytes, resulting in both a low platelet count and giant platelets on smear. Functionally, ristocetin-induced aggregation is markedly reduced and does not correct with normal plasma, which helps distinguish this from von Willebrand disease. The other conditions listed have different platelet size or function: Wiskott-Aldrich features small platelets with immunodeficiency; Hermansky-Pudlak involves platelet storage pool deficiency with albinism; Glanzmann thrombasthenia has normal-appearing platelets but defective GPIIb/IIIa–mediated aggregation.

Giant platelets on a smear point to macrothrombocytopenia caused by a platelet adhesion defect, most classically Bernard-Soulier syndrome. This disorder stems from a defective GPIb-IX-V receptor complex that binds von Willebrand factor, so platelets don’t adhere properly to damaged vessels. The consequence is impaired platelet production leading to unusually large platelets being released by the megakaryocytes, resulting in both a low platelet count and giant platelets on smear. Functionally, ristocetin-induced aggregation is markedly reduced and does not correct with normal plasma, which helps distinguish this from von Willebrand disease. The other conditions listed have different platelet size or function: Wiskott-Aldrich features small platelets with immunodeficiency; Hermansky-Pudlak involves platelet storage pool deficiency with albinism; Glanzmann thrombasthenia has normal-appearing platelets but defective GPIIb/IIIa–mediated aggregation.