Platelet count and function studies are performed on a patient with a history of easy bruising, and the following results are obtained:

Question

Test Result
Platelet count 295 ´ 109/L
Bleeding time Prolonged
Platelet aggregation with epinephrine Primary but no secondary wave
Platelet aggregation with low-dose adenosine
diphosphate (ADP) Primary but no secondary wave

Platelet aggregation with ristocetin Normal

What is the most likely diagnosis for this patient?

a. Bernard-Soulier disease
b. Dense granule deficiency
c. Glanzmann thrombasthenia
d. Gray platelet syndrome

Answer 1

ANS: B
The platelet count on this patient is normal; however, the bleeding time is abnormal, which suggests platelet dysfunction. Of the disorders listed, only dense granule deficiency has the platelet aggregation results that are listed. Patients with Bernard-Soulier disease have normal aggregation studies with every agonist except ristocetin, which is abnormal. The reverse is true for Glanzmann thrombasthenia: they have normal aggregation with ristocetin but have no primary wave, as well as no secondary wave with other agonists. Patients with gray platelet syndrome have a moderate thrombocytopenia, prolonged bleeding time, and large platelets that appear gray on a Wright-stained blood film because of the absence of a-granules. Platelet aggregation studies are unremarkable.