Extensive Deep Vein Thrombosis and Pulmonary Embolism in a Young Patient With Heterozygous Factor V Leiden Mutation and Antiphospholipid Syndrome.

Although thrombotic events are uncommon in young individuals, patients with genetic mutations in coagulation factors may develop extensive multisite thrombosis. We present the case of a 26-year-old patient, a smoker for nine years, who was admitted to the hospital complaining of right thigh pain with swelling, right flank abdominal pain, dyspnea, and hemoptysis. A medical history provided by the patient indicated that one month prior to presentation, an accidental fall had resulted in multiple rib fractures, bilateral hemopneumothorax, and pneumomediastinum. These injuries were treated with bilateral pleurotomy and passive pleural drainage. Upon initial presentation, the electrocardiogram (ECG) exhibited a distinctive pattern indicative of pulmonary embolism (PE), specifically sinus tachycardia and the S1Q3T3 pattern. Additionally, the thoraco-abdominopelvic angio-CT revealed acute PE in the branches of the pulmonary arteries supplying the bilateral lower lobes and deep vein thrombosis in the right external iliac vein, right common iliac vein with a protruding filling defect of approximately 18 mm in the inferior vena cava and extension to the left common iliac vein. Furthermore, a Doppler ultrasound of the right lower extremity revealed the presence of thrombosis along the entire right femoro-popliteal axis. Subsequent screening for hereditary thrombophilia revealed a heterozygous factor V Leiden G1691A* mutation and elevated levels of anticardiolipin antibodies. Despite the patient's compliance with non-vitamin K antagonist oral anticoagulants (NOACs) following discharge, a new thrombotic event, left femoral-popliteal venous axis thrombosis, occurred after a three-month interval. Repeat testing for anticardiolipin antibodies revealed an elevated titer, leading to a diagnosis of antiphospholipid syndrome. Given this diagnosis, anticoagulation with an antivitamin K was initiated. Screening for hereditary thrombophilia is crucial in young patients with thromboembolic events, as genetic causes may influence the therapeutic management and duration of anticoagulant treatment.