ACQUIRED CYCLIC THROMBOCYTOPENIATHROMBOCYTOSIS WITH PERIODIC DEFECT OF PLATELET-FUNCTION

A periodic fall of platelet number characterizes an acquired pathologi cal condition named cyclic thrombocytopenia. We observed a patient in whom the episodes of thrombocytopenia (platelet number less than 50 x 10(9)/l) were followed regularly by thrombocytosis (700-2300 x 10(9) p latelets/l). The period of platelet count fluctuation was about 40 d. Morphological examination of bone marrow showed the cyclic disappearan ce of mature and immature megakaryocytes: bone marrow cultures reveale d a periodic severe defect of both multilineage and single-lineage pro genitor cell growth. When platelet count was falling, a mild defect of platelet aggregation and ATP release was observed, while platelet fun ction was normal when platelet count was rising. Prednisone, thymopent ine. high-dose intravenous gamma-globulin and splenectomy were without effect. After 4 years of cyclic platelet and megakaryocyte fluctuatio ns, stable amegakaryocytic thrombocypenia developed and the patient di ed of haemorrhagic stroke.