Fatal HHV6 infection in an immunocompromised patient presenting with skin involvement

Infection with human herpesvirus-6 (HHV6) has a broad distribution in the human population, with a seroprevalence approaching 100% worldwide. Primary infection takes place during childhood, after which the virus remains latent mostly in lymphocytes and monocytes at various sites. Immunosuppression can result in viral reactivation, associated with clinical sequelae and even death. We report a case of a disseminated HHV6 infection in a 53-year-old patient, who was immunocompromised after allogeneic bone marrow transplant treatment for acute lymphocytic leukemia. Initially, he presented with a macular eruption of the skin, followed by involvement of other sites. Histopathologic analysis of skin biopsies revealed superficial perivascular large atypical mononuclear cells with intranuclear and intracytoplasmic inclusions. Most affected cells labeled with antibodies to CD3 and CD43 as lymphocytes, and some labeled with CD68 as macrophages. Polymerase chain reaction (PCR) studies of the blood, skin, liver, colon, cerebrospinal fluid and brain were positive for HHV6 virus. Additionally, the serologic titers for HHV6 were high. Viral particles were also detected by electron microscopy (EM) in the colon. Although rare, HHV6 virus may be an important pathogen in immunocompromised patients, and may present initially in the skin. Awareness of this infection is critical to diagnosis in acute settings.