Phenotype variability of patients with post polycythemia vera and post essential thrombocythemia myelofibrosis is associated with the time to progression from polycythemia vera and essential thrombocythemia.

This study indicates that the median time of transformation into SMF within a large cohort of 781 progressed patients was 11 years from diagnosis of PV and ET. The MYSEC project discloses a variability of the clinical phenotype of SMF depending by the time to progression from PV or ET. We found that the longer the TTP, the greater the spleen and the lower the hemoglobin. Our study findings basically identify a more advanced phenotype and suggest to carefully monitor these parameters in the management of the chronic phase of PV and ET. CALR genotype is associated to a more slowly progressive disease: this might be a useful information in defining a “genotypedriven” follow up for ET patients.