title: AA line.
abstract: BACKGROUND
  The transverse skin line of the upper part of the forearm is a common, easily recognized condition; however, this line has not been defined clearly and does not correspond to other previously reported skin lines. Our purpose was to assess the nature and associated conditions of this skin line, and characterize the histopathologic features.
  
  
  METHODS
  We examined 1343 healthy Korean people. The persons showing this skin line were evaluated by history and physical examination. Skin biopsy was performed on 10 persons showing this line: on one side at both the lesion and contralateral, non-lesion sites.
  
  
  RESULTS
  A total of 480 persons (36.4%) showed this line. The incidence was significantly higher in the female group and in the group between 10 and 19 years of age. Histopathologic examination showed subtle edema, separation and fragmentation of collagen bundles, and vasodilation at the transverse skin line.
  
  
  CONCLUSIONS
  We conclude that this skin line represents a newly defined skin line, and propose the term AA line.
authors.affiliation: Department of Dermatology, Yonsei University Wonju College of Medicine, South Korea.
authors.forename: S K
authors.initials: SK
authors.lastname: Ahn
authors.forename: S J
authors.initials: SJ
authors.lastname: Kim
authors.forename: E H
authors.initials: EH
authors.lastname: Choi
authors.forename: S H
authors.initials: SH
authors.lastname: Lee
authors.forename: S
authors.initials: S
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D002648:Child; D002675:Child, Preschool; D005260:Female; D005542:Forearm; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D008875:Middle Aged; D017678:Sex Distribution; D012871:Skin Diseases / Q000473:pathology*