Latent JAK2 V617F-Positive Myeloproliferative Neoplasm With Normal Blood Counts and Recurrent Splanchnic Vein Thrombosis in a Young Woman.

Latent myeloproliferative neoplasms are diagnostically challenging clonal hematopoietic disorders characterized by the JAK2 V617F mutation without overt hematologic abnormalities. This case report describes a 33-year-old woman presenting with recurrent splanchnic vein thrombosis, splenomegaly, and a history of unprovoked pulmonary embolism, found to have a JAK2 V617F-positive latent myeloproliferative neoplasm. Despite normal blood counts and unremarkable bone marrow findings, molecular testing confirmed the JAK2 V617F mutation (17% allele frequency), highlighting its critical role in diagnosing occult myeloproliferative neoplasms in patients with unexplained thrombosis. The patient's recurrent thrombotic events, including portal and mesenteric vein thrombosis, underscore the prothrombotic phenotype driven by JAK2 V617F mutation. Management included indefinite anticoagulation with apixaban, low-dose aspirin, and hydroxyurea to mitigate thrombotic risk and address the underlying clonal process. This case emphasizes the importance of molecular testing for JAK2 V617F in young patients with recurrent or unusual-site thrombosis, even with normal hematologic parameters, and the need for tailored therapeutic strategies to prevent complications and monitor disease progression.