Culture-Negative Lemierre's Syndrome: A Case Report of Septic Thrombophlebitis With Multi-organ Involvement.

Lemierre's syndrome is a rare and potentially life-threatening condition characterized by septic thrombophlebitis of the internal jugular vein, typically following an oropharyngeal infection. We report a case of a young, previously healthy patient who presented with sepsis and multi-organ involvement, later diagnosed with right internal jugular vein thrombosis. Despite negative blood cultures, clinical features supported a diagnosis of Lemierre's syndrome. The patient was treated with broad-spectrum antibiotics and anticoagulation, later complicated by hemoptysis requiring adjustment of therapy. This case brings attention to the diagnostic challenges in culture-negative Lemierre's syndrome and underscores the importance of early recognition, imaging, and individualized management, particularly in the absence of standardized guidelines for antibiotic and anticoagulant duration.