Our 61 year-old female patient presented with severe right-sided headache of 2 weeks and several days of encephalopathy. On examination, she was found to have left hemiparesis. She underwent multiple MRI brain studies which demonstrated nodular areas of enhancement involving the bilateral gangliocapsular region and left periventricular/left caudate. Associated T2 hyperintensities involved the right basal ganglia and left frontal subcortical white matter. Initial cerebrospinal fluid studies revealed a white blood cell count of 450/uL with lymphocytic predominance, protein 125 mg/dL, glucose 67 mg/dL, and negative autoimmune encephalopathy panel.
Subsequently, brain biopsy targeting a left frontal lesion demonstrated mild lymphohistiocytic infiltrate. The inflammatory cells were comprised of CD3+ T-cells with perivascular accumulation and parenchymal extension. There was no evidence of neoplastic, infectious, demyelinating, or vasculitic processes on histopathology.
Intravenous corticosteroids were trialed outpatient (methylprednisolone 1 gram for 3 days with month-long prednisone taper). MRI brain with and without contrast was repeated after treatment, with interval resolution of the enhancing lesions and associated decrease in prior T2 abnormalities. Clinically, she remained stable with residual mild left hemiparesis. Notably, her presentation resembled the initial clinical presentation in the index case report—headache with hemiparesis.