Mediastinal abscess and osteomyelitis as side effects of immunomodulatory treatment with fingolimod

Multiple sclerosis (MS) is the most common immune-mediated inflammatory demyelinating disease of the central nervous system. The immunomodulatory agents such as fingolimod used to treat the disease have been associated with several side effects, including severe infections. A mediastinal abscess with sternal osteomyelitis was never attributed to fingolimod therapy. It is usually associated with high morbidity and mortality and may follow a fulminant or subacute clinical course. Surgical exploration with drainage and debridement is the gold standard for effective treatment that protects against recurrence, mediastinitis and septic complications. Occasionally, when a mediastinal abscess coexists with sternal osteomyelitis, surgical debridement is followed by local negative pressure wound therapy or vacuum-assisted closure (VAC), prior to subsequent delayed pectoral flap or omental flap repair. Simultaneously, a meticulous study should be done to detect the origin of every mediastinal abscess. Esophageal ruptures, odontogenic infections, trauma complications and peritonsillar abscesses are the main causes. Rarely, hematogenous spread from other primary locations may lead to mediastinal abscess formation. Herein, we present such an unusual case of an immunocompromised patient with hematogenous dissemination in the setting of sacrococcygeal osteomyelitis secondary to treatment with fingolimod. A 54-year-old female patient with relapsing-remitting multiple sclerosis was referred to us from another hospital after 48 h of hospitalization with a diagnosis of mediastinal abscess. The patient was severely disabled due to multiple sclerosis, bedridden for the last 3 months, and received immunomodulatory treatment with fingolimod 0.5 mg once daily. She presented with a large tender mass in the anterior thoracic wall, substernal pain, fever, night sweats, confusion, and tachypnea. On admission, the blood test results indicated a severe infection: white cell count 19500/µl, and C-reactive protein 18.4 mg/dl. Full body computed tomography (CT) revealed an extensive abscess of the anterior thoracic wall in contact with the large substernal mediastinal abscess and fragmentation of the middle sternal portion (Figures 1 A, B). A significant collection of air was noted inside both cavities. There were similar findings in the sacrococcygeal region with fluid and air collection, probably as a complication of decubitus ulcers. The patient was treated with broad-spectrum...


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