title: Human herpesvirus-6-associated acute lymphadenitis in immunocompetent adults.
abstract: In contrast to other causes of herpetic lymphadenitis, the histological features associated with human herpesvirus-6 (HHV-6) infection have remained elusive since its discovery in 1986. We describe the histologic and phenotypic changes associated with acute HHV-6 lymphadenitis in two immunocompetent adults who presented with fever, fatigue, generalized lymphadenopathy, and elevated liver enzymes. Serologic tests for human immunodeficiency virus, acute Epstein-Barr virus, and cytomegalovirus infection were negative. Lymph node biopsies were consistent with viral lymphadenitis. Intranuclear and cytoplasmic inclusions were identified in CD4-positive T lymphocytes in expanded paracortical areas. Immunohistochemical staining with monoclonal antibody to the HHV-6 gp60/110 kDa envelope glycoprotein showed that the inclusions were positive for viral antigen. Electron microscopy demonstrated numerous viral particles in the cytoplasm and nucleus, characteristic of Herpesviridae family. Clustering of viral particles was observed, which has previously been reported only in infected tissue culture cells. PCR followed by sequencing of DNA extracted from the lymph nodes identified the virus as HHV-6, type B. This is the first report that documents distinctive histologic features of HHV-6 lymphadenitis and demonstrates that the cells harboring the virus in vivo are CD4-positive T lymphocytes.
authors.affiliation: Laboratory of Pathology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Irina
authors.initials: I
authors.lastname: Maric
authors.forename: Ron
authors.initials: R
authors.lastname: Bryant
authors.forename: Mones
authors.initials: M
authors.lastname: Abu-Asab
authors.forename: Jeffrey I
authors.initials: JI
authors.lastname: Cohen
authors.forename: Angelica
authors.initials: A
authors.lastname: Vivero
authors.forename: Elaine S
authors.initials: ES
authors.lastname: Jaffe
authors.forename: Mark
authors.initials: M
authors.lastname: Raffeld
authors.forename: Maria
authors.initials: M
authors.lastname: Tsokos
authors.forename: Peter M
authors.initials: PM
authors.lastname: Banks
authors.forename: Stefania
authors.initials: S
authors.lastname: Pittaluga
mesh_terms: D000328:Adult; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000648:ultrastructure; D005260:Female; D015654:Herpesvirus 6, Human; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D002479:Inclusion Bodies / Q000648:ultrastructure / Q000821:virology; D008198:Lymph Nodes / Q000378:metabolism / Q000473:pathology* / Q000821:virology; D008199:Lymphadenitis / Q000276:immunology / Q000473:pathology* / Q000821:virology*; D008297:Male; D046529:Microscopy, Electron, Transmission; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D019349:Roseolovirus Infections / Q000276:immunology / Q000378:metabolism / Q000473:pathology*