<unk>  is diagnosed in a patient with a<unk>  course of the disease, finding JC virus DNA in spinal fluid together with consistent white-matter lesions on brain magnetic resonance imaging (MRI); alternatively, a brain biopsy is diagnostic when the typical histopathology of demyelination, bizarre astrocytes, and enlarged oligodendroglial nuclei are present, coupled with techniques showing the presence of JC virus. Characteristic evidence of<unk>  on brain CT scan images are<unk> , noncontrast enhancing hypodense lesions without mass effect, but MRI is far more sensitive than CT. The most common area of involvement is the cortical white matter of frontal and parieto occipital lobes, but lesions may occur anywhere in the brain, such as the basal ganglia, external capsule, and posterior cranial fossa structures such as the brain stem and cerebellum. Although typically<unk> , natalizumab-associated<unk>  is often monofocal, predominantly in the frontal lobe.
Progressive multifocal leukoencephalopathy
Toxic leukoencephalopathy
Tuberculous meningitis
Granulomatous meningoencephalitis
Herpesviral encephalitis
Malignant multiple sclerosis
Drug-induced aseptic meningitis
Polioencephalitis