- Concurrent or previous central nervous system infections or neoplasms as revealed by Computerized Tomography (CT) or Magnetic Resonance Imaging (MRI) scan or cerebrospinal fluid analysis (such as toxoplasmosis, primary or metastatic Central Nervous System (CNS) lymphoma, progressive multifocal leukoencephalopathy, cryptococcal or other fungal meningitis, tuberculous Central Nervous System (CNS) infections, and untreated neurosyphilis).