title: Long-term treatment of photoaged human skin with topical retinoic acid improves epidermal cell atypia and thickens the collagen band in papillary dermis.
abstract: BACKGROUND
  Risk of photocarcinogenesis and the relevance of collagen in wrinkle effacement are two issues related to prolonged use of retinoic acid (RA) that have not been fully addressed.
  
  
  OBJECTIVE
  Our purpose was to investigate the degree of epidermal cellular atypia and the thickness of papillary dermal collagen in photoaging after long-term use of RA.
  
  
  METHODS
  Thirty-four subjects with photoaged skin were treated daily with 0.05% RA for at least 6 months. Epidermal cellular atypia was graded by means of a semiquantitative scale. Thickness of collagen band was measured by using image-analysis software.
  
  
  RESULTS
  Compared with pretreatment findings, melanocytic and keratinocytic atypia was significantly reduced and the collagen band thickness doubled.
  
  
  CONCLUSIONS
  This was an open-label study.
  
  
  CONCLUSIONS
  Improvement in epidermal cellular atypia is consistent with the ability of RA to act as a chemopreventive agent in epithelial carcinogenesis. Prolonged use also significantly increased collagen matrix deposition in dermal repair zones, which most likely contributes to wrinkle effacement by RA.
authors.affiliation: Department of Dermatology, University of Michigan Medical School, USA.
authors.forename: Soyun
authors.initials: S
authors.lastname: Cho
authors.forename: Lori
authors.initials: L
authors.lastname: Lowe
authors.forename: Ted A
authors.initials: TA
authors.lastname: Hamilton
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Fisher
authors.forename: John J
authors.initials: JJ
authors.lastname: Voorhees
authors.forename: Sewon
authors.initials: S
authors.lastname: Kang
mesh_terms: D000287:Administration, Topical; D003094:Collagen / Q000187:drug effects*; D000078404:Epidermal Cells; D004817:Epidermis / Q000187:drug effects*; D005260:Female; D006801:Humans; D008875:Middle Aged; D015595:Skin Aging / Q000187:drug effects* / Q000473:pathology*; D013997:Time Factors; D014212:Tretinoin / Q000008:administration & dosage*
chemical_list: D014212:Tretinoin; D003094:Collagen