Persistent Listeria monocytogenes Cerebritis Mimicking Cerebral Metastases Due to Melanoma.

Listeria cerebritis is a rare yet serious central nervous system infection, which can present with leptomeningeal enhancement, abscess, and seizures. An adult patient with a history of metastatic melanoma presented with left-sided weakness, later identified as postictal Todd's paralysis due to focal motor seizures. Further diagnostic workup revealed a leptomeningeal abscess in the setting of listeria cerebritis. The patient's condition improved after treatment with a prolonged course of ampicillin, gentamicin, and linezolid over eight weeks. Leptomeningeal disease in patients with cancer history is often thought to be metastatic disease but infections, such as listeria, should be considered even if cerebrospinal fluid is bland. Treatment of listeria may need to be prolonged in patients who are immunocompromised.