Coinfection of HHV 6 and HTLV-I Causing Encephalitis After Autologous Hematopoietic Stem Cell Transplantation: A Case Report and a Systematic Review of the Literature.

Background: A 52-year-old woman with multiple myeloma and asymptomatic human T lymphotropic virus (HTLV)-I infection underwent an autologous stem cell transplantation. Eighteen days after transplantation, she developed fever, headache, ataxia, and tremors. Coinfection of human herpesvirus 6 and HTLV-I encephalitis was diagnosed.

Methods: A systematic review of the literature was made. No article about HTLV I/II encephalitis in autologous stem cell transplantation was found. A total of 268 articles were screened and 8 matched the inclusion criteria. One was included by another source. Three of the 9 articles analyzed were excluded and 6 cases of human herpesvirus 6 encephalitis after ASCT were analyzed.

Results: The median patient age was 51 years. Multiple myeloma was the most common hematologic disease found. The median time since the hematopoietic stem cells transplantation was 19.5 days. Melphalan-based conditioning therapy was present in 83% of patients. All cerebrospinal fluid presented altered cell count and proteinorachia (median, 68.5 mg/dL). Most patients were treated with ganciclovir or foscarnet. In all cases, patients experienced a complete recovery.

Conclusion: HTLV-I encephalitis is an extremely rare disease that should be considered in patients previously infected. Human herpesvirus 6 encephalitis in patients after autologous hematopoietic stem cells transplantation is an uncommon situation but should be remembered in the differential in cases of acute confusional state. Prompt treatment may ensure complete recovery of the patient.