Clonal T cell-mediated cyclic thrombocytopenia.

Cyclic thrombocytopenia is a rare disorder characterized by periodic platelet count fluctuations of unknown aetiology. We report on a female patient with cyclic changes of platelet counts ranging from 6 x 10(9)/l to 753 x 10(9)/l in 4-week intervals. Platelet counts were inversely correlated to thrombopoietin levels suggesting production failure. Reticulocyte counts and neutrophil counts showed similar, but less prominent, fluctuations. Clonal T-cell receptor rearrangement was detected in bone marrow samples as well as in peripheral blood. Cell typing of blood lymphocytes revealed a relative increase in CD3+ T cells. Treatment with cyclosporine A resulted in a substantial improvement of platelet counts. Taken together, we provide evidence for clonal T-cell mediated bone marrow failure with cyclic impairment of thrombopoiesis responsive to cyclosporine therapy.