Reduced dense granules in platelet by electron microscopy in a patient with abnormal platelet aggregation with ADP and arachidonic acid: A case report of delta storage pool disorder.

Introduction: Delta storage pool disease (δ-SPD) is a platelet function disorder due to the decreased number and contents of dense granules causing bleeding symptoms. Diagnosis of δ-SPD is a complex procedure due to the variability of test results in platelet aggregometry and also it requires specialised tests. Electron microscopy (EM) is a promising tool to help in the diagnosis of this disorder. We report here a rare case of δ-SPD confirmed by EM.

Case report: A 42-year-old lady presented with prolonged bleeding history from a leech bite for 3 days. She also has a history of bleeding of variable severity for more than 20 years. On presentation, blood was oozing from the bite mark on her right wrist and there were multiple small bruises over her lower limbs. Full blood count, peripheral blood smear, coagulation profile, factor VIII assay, factor IX assay, von Willebrand Factor antigen and activity, bleeding time, and clot retraction test were normal. Platelet aggregation tests showed poor aggregation with ADP with a lag phase >60 seconds with arachidonic acid. There was poor ATP release reaction with ADP and arachidonic acid suggesting a storage defect. Subsequently, the EM of the platelets was performed and showed reduced dense granules indicating delta storage pool deficiency (δ-SPD). She was counselled about her diet and medication which seems to control her symptoms.

Conclusions: This case report highlights rare δ-SPD confirmed by EM. Diagnosis of this disorder is crucial in managing the patient. Highly specialised tests including platelet aggregometry, EM and molecular analysis are helpful in diagnosing this rare SPD.