Case Report: Non-bacterial thrombotic endocarditis and multiple thrombi uncover a hidden prothrombotic mutation

Non-bacterial thrombotic endocarditis (NBTE) is a rare, sterile valvular condition associated with hypercoagulable states, malignancy, or autoimmune diseases. Diagnosis is challenging due to nonspecific symptoms and unknown cause.

A 14-year-old male presented with acute-onset severe abdominal pain. Imaging studies revealed extensive thrombi involving multiple organ veins, as well as a large vegetation on the tricuspid valve, consistent with NBTE. Although routine thrombophilia screening was unremarkable, a significant family history of thrombotic events prompted further genetic evaluation. Whole-exome sequencing identified a pathogenic heterozygous variant in the F2 gene (F2 c.1621C > T, p.Arg541Trp), confirming an underlying hereditary thrombophilia. The patient underwent successful surgical excision of the vegetation with tricuspid valve repair. Anticoagulation therapy resulted in complete resolution of symptoms, and long-term management was initiated to mitigate recurrent thrombosis risk.

At one-year follow-up, repeat imaging showed recanalization of the portal and splenic veins without recurrent thrombosis, underscoring the effectiveness of anticoagulation.

This case demonstrates an atypical NBTE presentation with tricuspid valve involvement and extensive venous thrombosis due to a rare F2 mutation. The successful treatment reflects the importance of early recognition, multidisciplinary management and detailed consultation.