Presentation and outcome of patients with 2016 WHO diagnosis of prefibrotic and overt primary myelofibrosis

) were more represented in overt PMF. More patients with overt PMF were in higher International Prognostic Scoring System risk categories at diagnosis, and the frequency increased during follow-up, suggesting greater propensity to disease progression compared with pre-PMF. Median survival was significantly shortened in overt PMF (7.2 vs 17.6 years), with triple negativity for driver mutations and presence of HMR mutations representing independent predictors of unfavorable outcome. The findings of this "real-life" study indicate that adherence to 2016 WHO criteria allows for identification of 2 distinct categories of patients with PMF where increased grades of fibrosis are associated with more pronounced disease manifestations, adverse mutation profile, and worse outcome, overall suggesting they might represent a phenotypic continuum.