title: Characteristics of keratinocytes in facial solar lentigo with flattened rete ridges: comparison with melasma.
abstract: BACKGROUND
  Flattened rete ridges occurring on the face are not uncommon in solar lentigo (SL).
  
  
  OBJECTIVE
  To investigate the morphological changes of keratinocytes in facial SL with flattened rete ridges and melasma.
  
  
  METHODS
  In total, 25 patients with facial SL showing flattened rete ridges and 20 patients with melasma, in which rete ridge flattening is also a common feature, were included in the study. Skin biopsies were performed on lesional skin and perilesional normal skin.
  
  
  RESULTS
  The histological findings showed that the epidermis was significantly thicker in SL skin with flattened rete ridges compared with perilesional normal skin. Comparative quantitative analysis of epidermal morphology revealed that the individual keratinocytes were larger in size in lesional skin, without a significant change in the number of cells. Anti-p16 antibody staining was more intense in lesional epidermis, suggesting senescence of keratinocytes in the thickened epidermis. By contrast, melasma samples showed no significant difference in epidermal thickness or keratinocyte morphology in terms of number or size compared with normal skin.
  
  
  CONCLUSIONS
  These findings suggest that senescent changes in keratinocytes are important in the development of SL, even in the absence of rete ridge elongation, and the removal of keratinocytes harbouring melanin could be a possible strategy for SL treatment.
authors.affiliation: Department of Dermatology, Ajou University School of Medicine, Suwon, Korea.
authors.forename: J
authors.initials: J
authors.lastname: Shin
authors.affiliation: Department of Dermatology, Ajou University School of Medicine, Suwon, Korea.
authors.forename: J-Y
authors.initials: JY
authors.lastname: Park
authors.affiliation: Department of Dermatology, Ajou University School of Medicine, Suwon, Korea.
authors.forename: S J
authors.initials: SJ
authors.lastname: Kim
authors.affiliation: Department of Dermatology, Ajou University School of Medicine, Suwon, Korea.
authors.forename: H Y
authors.initials: HY
authors.lastname: Kang
mesh_terms: D000328:Adult; D000368:Aged; D005148:Facial Dermatoses / Q000473:pathology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D015603:Keratinocytes / Q000473:pathology*; D007911:Lentigo / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D056910:Republic of Korea; D012189:Retrospective Studies