Proinflammatory and prothrombotic conditions in JAK2V617F-positive MPN: a case of Lemierre's syndrome in essential thrombocythemia.

Lemierre's syndrome (LS) represents a rare yet potentially life-threatening systemic infection, characterized by thrombophlebitis of the internal jugular vein and abscess formation in distant organs. It typically follows episodes of tonsillitis or other infections of the oropharyngeal region. Pulmonary complications, including septic pulmonary emboli, are common. Essential thrombocythemia (ET) is a chronic myeloproliferative neoplasm (MPN) sometimes associated with the JAK2V617F mutation, which predisposes patients to thrombotic events. A 66-year-old male with JAK2V617F-positive ET presented with severe pulsatile pain radiating from the right temporal region to the occipital area following a recent dental infection. Although pain management was administered, the pain continued to persist. Computed tomography of the chest revealed multiple subpleural nodules, raising suspicion for septic pulmonary emboli. Further investigation with gadolinium-enhanced magnetic resonance imaging identified a thrombus extending from the right sigmoid sinus into the internal jugular vein, consistent with cerebral venous thrombosis. The patient was diagnosed with　LS, complicated by septic thrombosis. Blood cultures yielded alpha-hemolytic streptococcus. Empirical antimicrobial therapy combined with anticoagulation was initiated, resulting in a gradual improvement of symptoms, including the resolution of fever and pain. Follow-up imaging confirmed the resolution of both the infection and thrombosis. This is the first reported case of LS in a patient with JAK2V617F-positive ET. The coexistence of LS and JAK2V617F-positive MPN highlights the potential interplay between proinflammatory and prothrombotic conditions associated with the JAK2V617F mutation.