Pseudo-gray Platelet Syndrome
Case 96-4 |
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History/Physical Findings:A 76-year-old woman was admitted for management of a non-Q-wave myocardial infarction and acute pulmonary edema. She had an advanced diabetic heel ulcer and was treated for sepsis during her hospitalization. The past medical history included diabetes mellitus, bilateral carotid artery stenosis, and peripheral vascular disease. There is no reported history of bleeding or bruising.
Laboratory findings:
Peripheral Blood Smear - Wright's Stain  
Note the apparent lack of platelets on the peripheral blood smear and the above platelet count.
A careful review of the smear shows light grey agranular platelets.
 
This blood smear from the same patient was made with blood collected by fingerstick.
Discussion:In the presence of the anticoagulant EDTA, the patient's platelets appeared gray and agranular. When the blood sample was collected without exposure to EDTA, the platelets appear normal. There was a mild normochromic, normocytic anemia, but no RBC dysmorphology. The platelet count was within normal limits. There was no history to suggest platelet dysfunction.
The findings are consistent with pseudo gray platelet syndrome (PGPS). PGPS was described by Cockbill, Burmester, and Heptinstall (1988) who reported a 25-year-old woman with a history of mild bruising and bleeding. Bleeding time, activated partial thromboplastin time, prothrombin time, and euglobulin lysis time were within normal limits. There were no platelet antibodies detected. The patient's mother and two sisters had histories of easy bruising and heavy menstrual periods. A brother had no reported bleeding tendencies. Platelets from the mother, sisters, and a daughter were normal in number and appearance under the light microscope. Platelets in blood collected into EDTA appeared gray and agranular compared with platelets from blood in citrate or heparin. Under electron microscopy, EDTA-exposed platelets showed extensive activation, with loss of storage granule contents and pseudopod formation. Platelet aggregation studies were normal.
The abnormal platelet reaction following EDTA exposure is thought to be caused by a plasma factor, although not an immunoglobulin. The mechanism by which platelet activation occurs remains unknown. Few cases have been reported in the literature.
Pseudo-gray platelet syndrome differs from gray platelet syndrome (GPS), one of the giant platelet syndromes. GPS is characterized by thrombocytopenia, abnormally large agranular platelets in peripheral blood smears, and almost total absence of platelet alpha-granules and their constituents. The defect in GPS is the failure of megakaryocytes to package secretory proteins into alpha-granules. Patients with the GPS are affected by mild to moderate bleeding tendencies.
Diagnosis:Pseudo-gray platelet syndrome References:
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