Brain abscess in a rheumatoid arthritis patient treated with leflunomide - A case presentation and review

Immunosuppression is a significant parameter in the pathogenesis of brain abscesses (BA) and it could be the result of severe infections such as acquired immunodeficiency syndrome or drug-induced, by several medications used for systemic autoimmune diseases. Leflunomide is a pyrimidine synthesis inhibitor that affects the proliferation of lymphocytes and is used as a disease-modifying antirheumatic drug. Mild infections, particularly those of the respiratory tract and herpes zoster, are one of its most common adverse effects. However, atypical and severe infections have also been reported under treatment with leflunomide. A 70-year old female was referred to our hospital with headache, aphasia, and right-sided hemiparesis and a lesion of the left parietal lobe initially interpreted as a malignancy. Her medical history revealed a 12-year old history of rheumatoid arthritis under current treatment with leflunomide. A cerebral magnetic resonance imaging (MRI) revealed typical findings for a BA. She subsequently underwent a left craniotomy, which confirmed the MRI-based diagnosis. The abscess was evacuated and cultures were obtained intraoperatively. In the postoperative examination, the patient showed no neurological deficit. The differential diagnostic considerations in immunocompromised patients with neurologic deficits should include focal central nervous system infections such as a BA, even in the absence of fever or immunosuppressant-induced leukopenia. It also demonstrates the importance of early neurosurgical intervention for the prevention of sequelae. To the best of our knowledge, this is the second-to-date reported case of a BA under immunomodulatory therapy with leflunomide.