title: Acral lesions of vitiligo: why are they resistant to photochemotherapy?
abstract: BACKGROUND
  Acral lesions of vitiligo are usually resistant to conventional lines of treatment as well as surgical interventions.
  
  
  OBJECTIVE
  To clarify causes underlying resistance of acral lesions to pigmentation in vitiligo by studying some of the factors associated with mechanisms of repigmentation following photochemotherapy.
  
  
  METHODS
  The study included twenty patients with active vitiligo. Skin biopsies were taken from lesional and perilesional skin of areas expected to respond (trunk and proximal limb) and skin of acral areas, before and after PUVA therapy. Sections were stained with H and E, Melan-A, MHCII, CD1a, SCF and c-kit protein.
  
  
  RESULTS
  Before treatment acral areas showed significantly lower hair follicle density, melanocyte density, Langerhans cell (LC) density, epidermal MHCII expression, lesional SCF expression and perilesional c-kit expression. Following treatment with PUVA in both non-responsive acral and repigmenting non-acral lesions identical immunohistochemical changes in the form of significant decrease in LC density, epidermal MHC-II and SCF expression were observed.
  
  
  CONCLUSIONS
  The surprisingly similar histochemical changes in response to PUVA in acral and non-acral lesions did not manifest with clinical repigmentation except in non-acral ones. Factors such as inherent lower melanocyte density, lower melanocyte stem cell reservoirs and/or lower baseline epidermal stem cell factor may be considered as possible play makers in this respect.
authors.affiliation: Department of Dermatology, Faculty of Medicine, Cairo University, Cairo, Egypt.
authors.forename: S M
authors.initials: SM
authors.lastname: Esmat
authors.forename: A M
authors.initials: AM
authors.lastname: El-Tawdy
authors.forename: G A
authors.initials: GA
authors.lastname: Hafez
authors.forename: O A
authors.initials: OA
authors.lastname: Zeid
authors.forename: D M
authors.initials: DM
authors.lastname: Abdel Halim
authors.forename: M A
authors.initials: MA
authors.lastname: Saleh
authors.forename: T M
authors.initials: TM
authors.lastname: Leheta
authors.forename: M
authors.initials: M
authors.lastname: Elmofty
mesh_terms: D001706:Biopsy; D006801:Humans; D010778:Photochemotherapy; D011446:Prospective Studies; D014820:Vitiligo / Q000188:drug therapy* / Q000473:pathology