title: Prominent Langerhans' cell migration in the arthropod bite reactions simulating Langerhans' cell histiocytosis.
abstract: BACKGROUND
  Epidermal Langerhans' cells (LCs) play pivotal roles in cutaneous immune responses. An encounter with antigens or other stimuli causes the mobilization and migration of LCs. Therefore, some dermatoses, which originated from antigenic stimuli or trauma, can show LC migration. Recently, we experienced several cases of anthropod bites that showed marked inflammatory infiltrates with eosinophils and CD1a-positive LCs. It was difficult to differentiate these cases from Langerhans' cell histiocytosis (LCH).
  
  
  METHODS
  The degree and pattern of LC infiltration in the skin of arthropod bite reaction was evaluated. The characteristics of CD1a immunohistochemical expression in the arthropod bite reactions were compared with those of LCH.
  
  
  RESULTS
  A few arthropod bite cases (approximately 36%) showed extensive CD1a-positive LCs in the dermis, especially in the perivascular area. In addition, the CD1a expression patterns of LCs in the arthropod bite reactions were dendritic, whereas that of tumor cells in LCH were distinctly membranous and cytoplasmic.
  
  
  CONCLUSIONS
  Some arthropod bite reactions can show marked CD1a-positive LCs in the dermis, especially in the perivascular area. The dendritic CD1a immunohistochemical staining pattern in arthropod bite reactions is useful in helping to differentiate from LCH.
authors.affiliation: Department of Pathology, College of Medicine, Yonsei University, Seoul, Korea.
authors.forename: Se Hoon
authors.initials: SH
authors.lastname: Kim
authors.forename: Dong Hyun
authors.initials: DH
authors.lastname: Kim
authors.forename: Kwang Gil
authors.initials: KG
authors.lastname: Lee
mesh_terms: D000818:Animals; D018949:Antigens, CD1 / Q000378:metabolism; D001181:Arthropods; D002465:Cell Movement / Q000502:physiology*; D003937:Diagnosis, Differential; D006646:Histiocytosis, Langerhans-Cell / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D007299:Insect Bites and Stings / Q000473:pathology*; D007801:Langerhans Cells / Q000166:cytology / Q000378:metabolism
chemical_list: D018949:Antigens, CD1; C419393:CD1a antigen