title: EBV-Positive T/NK-Cell Lymphoproliferative Disease of Childhood.
abstract: BACKGROUND
  Epstein-Barr virus (EBV)-associated hemophagocytic lymphohistiocytosis (HLH), EBV-positive systemic T-cell lymphoproliferative disease (STLPD) of childhood, and chronic active EBV (CAEBV) infection may develop after primary EBV infection. This study reviewed the clinicopathological spectrum of EBV-associated T- and natural killer (NK)-cell LPD, including STLPD and CAEBV infection, with an analysis of T-cell clonality.
  
  
  METHODS
  Clinicopathological features of seven patients with EBV-associated HLH or STLPD and 12 patients with CAEBV infection were reviewed. Immunohistochemical staining and a T-cell receptor (TCR) gene rearrangement study were performed.
  
  
  RESULTS
  STLPD and EBV-positive HLH showed significantly overlapping clinicopathological findings. One patient with STLPD and one patient with EBV-positive HLH demonstrated moderate to severe atypia of the infiltrating lymphocytes, whereas the remaining patients lacked significant atypia. Twelve patients had CAEBV infection, four of whom suffered mosquito-bite hypersensitivity, five showed NK lymphocytosis, and one suffered hydroa vacciniforme. Infiltrating lymphocytes were predominantly small and devoid of atypia. Hemophagocytic histiocytosis was found in seven of 11 patients. Monoclonality was detected in three (50%) of the six patients with successful TCR gene analysis.
  
  
  CONCLUSIONS
  EBV-positive HLH and STLPD share similar clinicopathological findings and may constitute a continuous spectrum of acute EBV-associated T- or NK-cell proliferative disorders. The distinction of EBV-positive T-cell LPD from EBV-positive HLH may be difficult during routine diagnoses because of the technical limitations of clonality assessment.
authors.affiliation: Department of Pathology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Mineui
authors.initials: M
authors.lastname: Hong
authors.forename: Young Hyeh
authors.initials: YH
authors.lastname: Ko
authors.forename: Keon Hee
authors.initials: KH
authors.lastname: Yoo
authors.forename: Hong Hoe
authors.initials: HH
authors.lastname: Koo
authors.forename: Seok Jin
authors.initials: SJ
authors.lastname: Kim
authors.forename: Won Seog
authors.initials: WS
authors.lastname: Kim
authors.forename: Heejung
authors.initials: H
authors.lastname: Park
keywords: Clonality; Epstein-Barr virus infections; Killer cells, natural; Lymphoma, T-cell; Lymphoproliferative disorders