Non-HTLV-I associated pleomorphic T-cell lymphoma of the brain mimicking post-vaccinal acute inflammatory demyelination.

Two weeks after vaccination against tick-borne encephalitis (TBE), a 57-year-old female suddenly developed mental confusion and hemiparesis of the left side. Cranial MRI demonstrated extensive bilateral lesions in the fronto-parietal white matter of both hemispheres, suggesting an acute inflammatory demyelinating disease following vaccination. Despite administration of high-dose corticosteroids, the patient died 3 weeks after onset of neurological symptoms. Autopsy revealed diffuse infiltrates of a primary cerebral pleomorphic T-cell lymphoma of medium and large cell type. PCR on brain tissue for HTLV-I and serology for anti-HTLV-I antibodies in CSF and serum were negative; immunocytochemistry on brain tissue did not detect EBV-related antigen. This is the first recorded observation of a diffusely infiltrating primary central nervous system T-cell lymphoma, clinically and radiologically mimicking a fatal acute inflammatory demyelinating complication after vaccination.