Nocardia Brain Abscess Mimicking a Metastatic Brain Tumor: A Severe CNS Infection Requiring Aggressive Management

Nocardiosis is an uncommon Gram-positive bacterial infection caused by aerobic actinomycetes in the genus Nocardia. Nocardia spp. have the ability to cause localized or systemic suppurative disease in humans and animals. Nocardiosis is typically regarded as an opportunistic infection, but approximately one-third of infected patients are immunocompetent. We report a rare case of pulmonary nocardiosis and a brain abscess caused by Nocardia asteroides in an elderly woman with a history of Crohn’s disease. Radiographic imaging revealed a contrast-enhancing lesion with perilesional parenchymal edema that was preoperatively thought to be a neoplasm. The patient experienced aggressive disease progression simulating a metastatic brain tumor. Early diagnosis of norcadiosis, the absence of underlying disease, and the administration of appropriate antibiotics has a positive impact on prognosis. Familiarity with the magnetic resonance and computed tomography findings associated with CNS nocardiosis, such as those presented here, is essential for making an early diagnosis.