title: Effect of topical tretinoin on photoaged facial skin: a histometric, immunohistochemical and ultrastructural study.
abstract: BACKGROUND
  Topical tretinoin is a recognized treatment for photoageing.
  
  
  OBJECTIVE
  To evaluate the microscopic changes induced by topical tretinoin used to treat mild to moderate photodamage in dark-skinned patients aged 30 to 50 years.
  
  
  METHODS
  Biopsy specimens were obtained from the facial skin of 11 patients before and after treatment with topical tretinoin. Routine histopathology coupled with histometric computer-assisted image analysis was used to assess epidermal changes. Alcian blue stain was used to measure changes in glycosaminoglycans (GAGs). Immunoperoxidase technique for type I and III collagens and elastin, as well as transmission electron microscopy, were used to measure changes in collagen and elastic fibres.
  
  
  RESULTS
  Epidermal hyperplasia occurs following tretinoin application, which is reversible with continued therapy. GAGs decreased (p < 0.05) after 6 months of tretinoin application but with no significant change thereafter. Quantitatively, there was an insignificant decrease of type I (p = 0.7) and III (p = 0.3) collagens during the first 6 months of tretinoin usage. However, biopsies taken after 10 months revealed a statistically significant increase in collagen I from a mean of 75.2% +/- 9.6 before treatment to 94.2% +/- 4.1 after treatment (p = 0.05). Similarly, the amount of type III collagen increased from a mean of 74.6% +/- 9.96 to 90.6% +/- 2.1 after 10 months of treatment (p = 0.05). On the other hand, the amount of elastin significantly (p = 0.02) decreased from a mean of 54.5% +/- 3.68 before treatment to 43.4% +/- 4.42 after 6 months of tretinoin application but with no significant change thereafter. Such changes were associated ultrastructurally with new collagen deposition and improvement of the quality of elastic fibres.
  
  
  CONCLUSIONS
  Topical tretinoin benefits facial skin, mainly by increasing collagen I and III and also by improving the morphological appearance of collagen and elastic fibres.
authors.affiliation: Department of Dermatology, Faculty of Medicine, Al-Minya University, Al-Minya, Egypt. m_domyati@hotmail.com
authors.forename: Moetaz M
authors.initials: MM
authors.lastname: El-Domyati
authors.forename: Sameh K
authors.initials: SK
authors.lastname: Attia
authors.forename: Fatma Y
authors.initials: FY
authors.lastname: Saleh
authors.forename: Hesham M
authors.initials: HM
authors.lastname: Ahmad
authors.forename: Jouni
authors.initials: J
authors.lastname: Uitto