Researchers described the occurrence of thrombotic events in a cohort of children who had myeloproliferative neoplasms (MPNs) in a poster presented at the International Society on Thrombosis and Haemostasis (ISTH) 2021 Congress. The research was presented by Nicole Kucine, MD, MS, of Weill Cornell Medicine in New York, NY, and colleagues.

“There is limited literature focused on thrombotic events in younger patients with MPNs, and our objective was to describe the thrombotic events in a cohort of young MPN patients,” Dr Kucine explained in an audio presentation accompanying her team’s poster.

The researchers evaluated a cohort of 43 patients diagnosed with MPNs to assess the prevalence of thromboses, as well as characteristics of patients, including demographic and disease-specific information, experiencing arterial and/or venous thromboses in this population.

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The evaluated cohort included patients of ages ranging from 3 to 21 years, among whom there were 26 female and 17 male patients. A total of 6 of the patients had experienced thrombotic events, of whom 5 were female. The median age at first thrombotic event was 14.5 years (range, 5-18).

MPN subtypes that were represented among patients with thromboses included polycythemia vera in 2 patients, presumed polycythemia vera in 3 patients, and essential thrombocytosis in 1 patient. Thrombotic events consisted of arterial ischemic stroke in 1 patient, cerebral venous sinus thrombosis with pulmonary embolism in 1 patient, and Budd-Chiari syndrome in 4 patients; Budd-Chiari is a type of splanchnic vein thrombosis.

By mutational status, 5 of the 6 patients with thromboses showed JAK2V617F mutational status. However, no patients with thromboses had either CALR or MPL mutations.

Blood counts were examined in patients at the time of thrombosis. Thrombocytosis (>450 x 109 platelets/L) was seen in 5 of the patients, although extreme thrombocytosis (>1000 x 109 platelets/L) was not reported in any of the patients. Polycythemia, based on age- and sex-specific norms, was shown in 3 of the patients. Leukocytosis (>10 x 109 cells/L) was demonstrated in 4 patients.

“In summary, we can see that thrombotic events do happen in young MPN patients, and, as in adults, thrombotic events are more common in pediatric patients with the JAK2V617F mutation, and splanchnic vein thrombosis occurred exclusively in females in this young MPN cohort,” Dr Kucine concluded in her audio presentation.


Kucine N, Vanderpoel V, Shimano K. Thrombotic complications in a cohort of children with myeloproliferative neoplasms. Paper presented at: International Society on Thrombosis and Haemostasis (ISTH) 2021 Congress; July 17-21, 2021; virtual. Abstract LPB0123.