Chronic myeloid leukaemia with extreme thrombocytosis at presentation: Incidence, clinical findings and outcome

Chronic myeloid leukaemia (CML) usually presents with marked leucocytosis, but rare cases may present with an isolated, marked thrombocytosis, defined as a platelet count >1000 × 109/l (Turakhia et al, 2016).\r\n\r\nThe natural history and the optimal treatment of this entity are not well characterized. We have previously reported our monocentric experience (Sorà et al, 2014); based on these results, we evaluated the incidence, clinical characteristics and outcome of this CML variant in a large series of patients from 16 different Italian haematological centres.\r\n\r\nFrom January 2002 to December 2015, 87 of 1591 patients with extreme thrombocytosis were identified, with an estimated incidence of 5·5%. Patient characteristics are shown in Table 1. Coagulation tests were available in 59/87 patients (67·8%), of which only three (5%) had an abnormally prolonged activated partial thromboplastin time. These three patients were investigated for the presence of a non-specific inhibitor, such as antiphospholipid antibodies, and the levels of coagulation factors. In one patient, anti-cardiolipin antibodies were also detected and in another patient a protein C deficiency was identified. However, only a few patients had undergone a full investigation for congenital thrombophilia, including F2 (prothrombin) G20210A mutation and F5 R506Q (Factor V Leiden).