[Human herpesvirus 6 encephalitis in a patient with adult T-cell leukemia/lymphoma].

Human herpesvirus 6 (HHV-6) reactivates in immunocompromised patients, and HHV-6 encephalitis has often been reported as a complication of transplantation. We describe a 37-year-old woman with the acute type of adult T-cell leukemia/lymphoma who developed HHV-6 encephalitis before chemotherapy. The patient's main symptoms were disorientation and short-term memory loss. Magnetic resonance imaging of the brain showed a bilateral T2 prolongation within the temporal lobes, and HHV-6 DNA was detected in the cerebrospinal fluid (CSF). After treatment with ganciclovir, HHV-6 DNA disappeared from the CSF and the patient's symptoms gradually improved. HHV-6 encephalitis should be listed as a differential diagnosis of encephalopathy developing in immunocompromised patients.