Large granular lymphocytic proliferation-associated cyclic thrombocytopenia.

Cyclic thrombocytopenia is a rare condition characterized by regular fluctuations in the platelet count, resulting in bleeding at the time of platelet count nadir. We evaluated a male patient whose platelet count cycled between <10x10(9)/L and a maximum of >1300x10(9)/L over a median of every 42 days (range, 28-57 days). Antiplatelet antibodies were present at highest titer just prior to platelet nadirs. A pathologic expansion of CD3+CD57+ large granular lymphocytes (LGLs) along with a clonal rearrangement of the T-cell receptor (TCR) gamma gene in circulating T cells was detected. LGLs decreased in response to treatment with cyclosporine-A (CsA), but the cycling of the platelet count continued. This is the first report of cyclic thrombocytopenia associated with a T-LGL lymphoproliferative disorder. Copyright (c) 2005 Wiley-Liss, Inc.