1- Thrombocytosis > 600 G / l persistent

2- Bone marrow biopsy:

Proliferation of the megakaryocytic line with high proportion of large mature megakaryocytes

3- No index of:

·        Polycythemia vera

·        Chronic myelogenous leukemia

·        Osteomyelofibrosis

·        Myelodysplastic syndrome

·        Reactive thrombocytosis