Publication Only: Myeloproliferative neoplasms - Clinical
According to the WHO classification, the designation of myeloproliferative neoplasms unclassifiable (MPN-U) should be used for cases with clinical, morphologic, and molecular features of MPN failing to meet the diagnostic criteria of a specific entity. Reported incidence of MPN-U varies significantly in different studies with a range up to > 20%. However, most studies show an incidence of 10-15% or even less. When the 2016 WHO criteria have been applied, the incidence is reduced to <5%.
In this report we study the clinical and laboratory characteristics of 31 consecutive cases of unclassifiable myeloproliferative disease afferent to the center for myeloproliferative diseases of our Hematology Unit.
From 2010 to 2018 our center has collected 508 cases of Philadelphia-negative Myeloproliferative Neoplasms (MPNs). Data from these patients were collected in a specific database and analysed with simple statistic tools.
Among these 508 patients, 31 (6.2%) had a diagnosis of MPN-U, 16 male and 14 female. Median age at diagnosis was 60.9 years. 22/31 (70.9%) were JAK2 V617F positive, 3/31 were CALR mutated (0.96%), 2/31 (0.64%) MPL mutated and 6/31 (19.3%) resulted as triple negative (TN) for driver mutations. Data from the other groups of MPNs (PV, ET, overtMF and preMF) were analised as well and compared to the ones from the MPN-U group.
Chronic myeloproliferative diseases unclassifiable (MPN-U) represent the 6.2% of the cases relating to our center. No significant difference at diagnosis has been highlighted regarding sex, age and mutational status between MPN-U and MPN classified according to WHO 2016. The exact incidence of MPN-U is unknown. It is probable that frequency varies significantly according to the experience of the diagnostician and the specific classification system and criteria used. It is possible that careful use of the WHO 2016 classification may significantly reduce the frequency of MPN-U.