Essential thrombocythemia: a relative benign long-term course.

The disease manifestations, response to therapy, and follow-up course of 35 patients with essential thrombocythemia seen in a single center were evaluated. The median age was 53 years (range 17-81). Twelve patients were asymptomatic on presentation and the diagnosis was incidental. Twenty-three patients presented with thrombocytosis-related symptoms, most commonly neurological, microcirculatory, or thromboembolic. In no patient did hemorrhage occur as a presenting symptom. The mean platelet count (+/- SD) at diagnosis was 858 +/- 223 x 10(9)/l and the mean maximal count during the follow-up period was 989 +/- 269 x 10(9)/l. The median follow-up of the entire group was 54 months (range 12-172). Ten of the 12 patients who were asymptomatic on presentation remained so during the observation period, while 10 patients who presented with thrombocytosis-related symptoms became asymptomatic following a single course of treatment with no recurrence of symptoms. Thirty of the 35 patients were treated with busulfan or hydroxyurea or both. Response to cytoreductive therapy was prompt and continuous in most patients. Essential thrombocythemia might be a disease of grave consequence but it seems that in general its course under treatment is more benign than previously thought.