Lemierre's Syndrome Complicated by Descending Mediastinitis.

Lemierre's syndrome (LS) is a rare, potentially life-threatening complication of acute oropharyngeal infection that may progress to mediastinitis if treatment is delayed. We report a case of a 35-year-old woman with no prior medical history who had been using products promoting body mass gain, potentially corticosteroid-based, for three months. She presented with neck swelling, odynophagia, and fever for two weeks and reported New York Heart Association class III dyspnea. Contrast-enhanced cervicothoracic CT revealed laterocervical, parapharyngeal, and tonsillar abscesses extending to the anterior cervical region with air bubbles, a retrosternal collection, and right pericardial and pleural effusions, along with thrombosis of the superior vena cava, retromandibular vein, and external jugular vein. Laboratory analyses showed elevated inflammatory markers and purulent pleural fluid. A diagnosis of LS complicated by descending mediastinitis was made. The patient underwent drainage of the various collections, including thoracic drainage. Her condition improved satisfactorily with surgical treatment, antibiotics, anticoagulation, and local care, and she was subsequently discharged from the hospital. LS is a serious condition that can lead to life-threatening complications such as mediastinitis, requiring rapid, multidisciplinary, and appropriate management.