Organ Stiffness in the Work-Up of Myelofibrosis and Philadelphia-Negative Chronic Myeloproliferative Neoplasms

To define the role of spleen stiffness (SS) and liver stiffness (LS) in myelofibrosis and other Philadelphia (Ph)-negative myeloproliferative neoplasms (MPNs), we studied, by ultrasonography (US) and elastography (ES), 70 consecutive patients with myelofibrosis (MF) (no.43), essential thrombocythemia (ET) (no.10), and polycythemia vera (PV) (no.17). Overall, the median SS was not different between patients with MF and PV (p= 0.9); however, both MF and PV groups had significantly higher SS than the ET group (p= 0.011 andp= 0.035, respectively) and healthy controls (p< 0.0001 andp= 0.002, respectively). In patients with MF, SS values above 40 kPa were significantly associated with worse progression-free survival (PFS) (p= 0.012; HR = 3.2). SS also correlated with the extension of bone marrow fibrosis (BMF) (p< 0.0001). SS was higher in advanced fibrotic stages MF-2, MF-3 (W.H.O. criteria) than in pre-fibrotic/early fibrotic stages (MF-0, MF-1) (p< 0.0001) and PFS was significantly different in the two cohorts, with values of 63% and 85%, respectively (p= 0.038; HR = 2.61). LS significantly differed between the patient cohort with MF and healthy controls (p= 0.001), but not between the patient cohorts with ET and PV and healthy controls (p= 0.999 andp= 0.101, respectively). We can conclude that organ stiffness adds valuable information to the clinical work-up of MPNs and could be employed to define patients at a higher risk of progression.