[Clinical characterization of essential thrombocythemia in comparison with other myeloproliferative diseases and reactive thrombocytoses].

60 patients with essential thrombocythemia (ET) have been retrospectively and prospectively followed from 1974 through 1987. The presenting signs and symptoms and the course of the disease were analyzed and compared to 10 patients with persisting reactive thrombocytosis selected from 6,000 patients with reactive thrombocytosis and to 50 patients with other myeloproliferative diseases. 54 ET-patients presented with complications, 46 with thrombembolic, 3 with hemorrhagic problems and 5 with thrombembolic and hemorrhagic problems. In 6 patients ET was detected accidentally. Disturbances of the microcirculation, mainly of the fingers and the toes, were the most frequent symptom. The average maximal platelet count was 1,207,000/microliter. The average platelet count at diagnosis was 880,000/microliter. 16 patients had an elevation of the serum creatinine at diagnosis, which deteriorated during the course of the disease. Bone marrow examinations were performed in 56 patients, histology in 48 patients, cytology in 29 patients. In contrast to the clinical diagnosis the histological diagnosis was in 4 cases each polycythemia vera and myeloproliferative syndrome without further specification. 12 patients died thus far. The causes of death were thrombembolic complications in 9, acute leukemia in 2 patients, in 1 patient the cause of death is not known. 10 years after diagnosis 61% of the patients are still alive. It appears that ET is a more important risk factor for the disturbances of the micro- and macrocirculation than has been recognized until now. ET is, if thrombembolic complications are avoided, a disease with a relatively benign course.