Idiopathic concomitant pulmonary embolism and peripheral arterial thrombosis in a young adult: A diagnostic challenge

We report the rare case of idiopathic concomitant pulmonary embolism (PE) and peripheral arterial thrombosis in a previously healthy 30-year-old male. The patient presented with acute dyspnea, left lower limb pain, and transient hemiparesis. Examination revealed tachypnea, hypoxia, and absent peripheral pulses in the lower limbs. Electrocardiography showed S1Q3T3 changes, and imaging confirmed bilateral PE and extensive arterial occlusions in both lower limbs. Despite thorough evaluation – including autoimmune serologies, inherited thrombophilia screening, vasculitis markers, and cardiac imaging – no definitive prothrombotic condition or embolic source was identified. The presence of a small atrial septal defect with a left-to-right shunt ruled out confirmed paradoxical embolism, and while deep vein thrombosis was not visualized in calf veins, thrombus was detected in the femoral and popliteal veins. The patient was managed conservatively with anticoagulation, resulting in clinical improvement. This case highlights the diagnostic challenges posed by idiopathic thromboembolic events in young adults and underscores the importance of maintaining a broad differential diagnosis. While rare, such cases necessitate early recognition, detailed investigation, and timely intervention to prevent life-threatening outcomes.