title: De novo melanoma and melanoma arising from pre-existing nevus: in vivo morphologic differences as evaluated by confocal microscopy.
abstract: BACKGROUND
  Although in the majority of melanomas there is no evidence of pre-existing melanocytic nevus, it is believed that malignant transformation may sometimes occur within a benign precursor.
  
  
  OBJECTIVE
  We sought to describe the morphologic features of de novo melanoma and melanoma arising from nevi by means of in vivo confocal microscopy, and to correlate them with their corresponding histopathologic features.
  
  
  METHODS
  A total of 113 consecutive, histopathologically proven melanoma cases, 33 arising from a nevus and 80 occurring de novo, were imaged by confocal microscopy and retrospectively evaluated. Cyto-architectural features preferentially expressed in melanomas arising from nevi and in de novo melanomas were defined.
  
  
  RESULTS
  By confocal microscopy, abrupt transition, localized distribution of junctional atypical cells, and the presence of dense dermal nests were the most helpful criteria for categorizing a melanoma as arising from a nevus. Melanomas arising from common and congenital nevi were predominantly composed of roundish, monomorphous cells, whereas melanomas arising either de novo or from dysplastic nevi were characterized by markedly pleomorphic cells.
  
  
  CONCLUSIONS
  The study is retrospective.
  
  
  CONCLUSIONS
  Confocal microscopy is effective in identifying melanoma even when a nevus is simultaneously present, confirming the clinical usefulness of this methodology. Moreover, distinctive features were observed in de novo melanomas and melanomas arising from nevi, permitting accurate distinction between the two groups. Finally, differences in cell morphology, easily detectable by confocal microscopy, seemed to characterize different melanoma types.
authors.affiliation: Department of Dermatology, University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Caterina
authors.initials: C
authors.lastname: Longo
authors.affiliation: Department of Pathology, University Federal of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Cintia
authors.initials: C
authors.lastname: Rito
authors.affiliation: Department of Anatomy and Histology, University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Beretti
authors.affiliation: Department of Pathology, University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Cesinaro
authors.affiliation: Department of Pathology, University Federal of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Juan
authors.initials: J
authors.lastname: Piñeiro-Maceira
authors.affiliation: Department of Dermatology, University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Seidenari
authors.affiliation: Department of Dermatology, University of Modena and Reggio Emilia, Modena, Italy. Electronic address: pellacani.giovanni@unimore.it.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Pellacani
mesh_terms: D000328:Adult; D000368:Aged; D046169:Dermoscopy; D004416:Dysplastic Nevus Syndrome / Q000150:complications / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008545:Melanoma / Q000209:etiology / Q000473:pathology*; D018613:Microscopy, Confocal; D008875:Middle Aged; D009508:Nevus, Pigmented / Q000150:complications / Q000473:pathology*; D012878:Skin Neoplasms / Q000473:pathology*