JAK2 (V617F) Mutation and Cerebral Venous Thrombosis,

Whether or not cerebral venous thrombosis, such as splanchnic venous thrombosis, can be the first manifestation of an underlying myeloproliferative neoplasm is currently unclear.

Patients with cerebral venous thrombosis were tested for the JAK2 (V617F) mutation within one year from the onset of thrombosis and were followed until the development of a myeloproliferative neoplasm or censored at the end of follow-up.

Ten of 152 patients (6.6%) carried the JAK2 (V617F) mutation. Three of them had known acquired risk factors for thrombosis and 5 had thrombophilia. The median duration of follow-up was 7.8 years (6 months to 21.3 years). Six patients met the diagnostic criteria for myeloproliferative neoplasm at the time of cerebral venous thrombosis, while three additional patients developed the disease during the follow-up, for an annual incidence of 0.26% patient-years (95% CI 0.05–0.64). The last patient has no evidence of disease after three years of follow-up. Patients without the JAK2 (V617F) mutation at the time of cerebral venous thrombosis were re-tested at the end of the follow-up and remained negative, with normal whole blood counts [log-rank test c²: 159 (p<0.0001)]. Hence, a myeloproliferative neoplasm was diagnosed in 90% of patients with the JAK2 (V617F) mutation and in none of those without (Fisher's exact test p<0.0001).

Cerebral venous thrombosis can be the first symptom of a myeloproliferative neoplasm. Thus, patients with cerebral venous thrombosis should be tested for the JAK2 (V617F) mutation, irrespective of whole blood counts and the presence of other risk factors for thrombosis.

No relevant conflicts of interest to declare.