[Cyclic thrombocytopenia complicated with Sjögren syndrome and the mechanism of periodic platelet count fluctuation].

Cyclic thrombocytopenia is a rare disorder with periodic changes of the platelet count. We experienced a patient with cyclic thrombocytopenia and Sjögren syndrome (SS), and studied the mechanism of the cyclic changes of the platelet count. The patient, a 75-year-old woman, was referred to our hospital because of dry mouth, dry eyes, and severe thrombocytopenia. Her platelet count varied from 0.2 x 10(4)/microl to 22.7 x 10(4)/microl in 14-28-day cycles. Anti-SS-A/Ro antibody and Schirmer's test were positive. Histological examination of the salivary glands revealed infiltration of inflammatory cells, leading to the diagnosis of SS. There was an inverse relation between the platelet count and serum levels of PA-IgG. When the platelet count was low, the number of bone marrow megakaryocytes and the colony counts of CFU-Meg decreased. The serum thrombopoietin level increased at the nadir of the platelet count and decreased as platelets increased. After prednisolone therapy, her platelet count increased along with the improvement of sicca symptoms. These findings suggest that platelet fluctuation is due to the periodic increase of platelet destruction, as well as periodic failure of platelet production.