Platelet Delta Storage Pool Deficiency In Children : A Case Series

Delta storage pool deficiency (δ-SPD) is a rare group of platelet disorders characterized by a reduction in the number or content of dense granules. δ-SPD causes a mild to moderate bleeding diathesis characterized mainly by mucocutaneous bleeding. A suspected case of δ-SPD can be diagnosed by the patient’s presentation, a family history and suggestive clinical bleeding or preliminary laboratory results such as a typical platelet aggregation pattern, characterized by normal aggregation with ristocetin and lack of second wave of aggregation with ADP or epinephrine. However not all patients have a typical presentation. This is a review of 6 pediatric patients with δ-SPD at our institution.

We have 3 male and 3 female children with a confirmed diagnosis of δ-SPD. Their current age ranges from 19 months-17 years. Four of the 6 patients are Hispanic and 2 Caucasian. A positive family history of excessive bleeding was obtained in 4 patients. The youngest patient was 2 weeks at diagnosis. Epistaxis was the most common presenting symptom. The youngest patients in the group presented with subdural hematomas before the age of 2. The 17 year old presented with significant menorrhagia and anemia, requiring red cells and platelet transfusions in addition to antifibrinolytic agents and oral contraceptives.

The preliminary work up in all patients included a CBC, PT, PTT and platelet function analysis (PFA).PFA was reported as abnormal in only 1 patient and was not accurate in another patient due to platelet clumping. Platelet aggregation studies and Von Willebrand’s panel were done and reported as normal in 5 patients. Platelet count ranged from 248,000- 552,000/mm³. Electron microscopy ranged from 1.69-3.59 dense granule/platelet (normal 4-6 dense granule/platelet).

All of the patients were primarily managed by preventive measures and antifibrinolytic agents. Platelet transfusions have been reserved for life threatening bleeds or surgical procedures.

The presentation of this rare bleeding disorder is not limited to mucocutaneous bleeding. Presenting symptoms in the very young could be limited to an intracranial hemorrhage. Electron microscopy to diagnose this condition should be pursued despite normal platelet function and aggregation studies, especially in patients with a high index of suspicion based on their clinical presentation or family history.

No relevant conflicts of interest to declare.