title: Thrombocytopenic purpura with giant platelets and ultrastructural platelet defects.
abstract: The case of a patient with thrombocytopenia and giant platelets is presented. Platelet function tests including bleeding time, aggregation, availability of PF3, and serotonin uptake and release were abnormal. A bone marrow aspirate showed megakaryocytes that while not increased in number, were young in appearance. Electron microscopy of platelets revealed a dilated surface-connecting canalicular system and a prominent membrane complex. No similar findings were encountered among the patient's relatives. The various diagnostic possibilities in this patient are discussed.
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000293:Adolescent; D001323:Autoantibodies / Q000032:analysis; D001780:Blood Coagulation Tests; D001792:Blood Platelets / Q000276:immunology / Q000473:pathology* / Q000648:ultrastructure; D003094:Collagen / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology; D005260:Female; D006801:Humans; D010974:Platelet Aggregation / Q000187:drug effects; D011696:Purpura, Thrombocytopenic / Q000097:blood*; D012310:Ristocetin / Q000494:pharmacology
chemical_list: D001323:Autoantibodies; D012310:Ristocetin; D000244:Adenosine Diphosphate; D003094:Collagen; D004837:Epinephrine