title: Dermoscopic features of difficult melanoma.
abstract: BACKGROUND
  The dermoscopic diagnosis of cutaneous melanoma (CM) may be difficult because some CM lack specific dermoscopic features for melanoma diagnosis.
  
  
  OBJECTIVE
  To evaluate whether a diagnosis of CM could be achieved using the classic dermoscopic melanoma-specific criteria, we conducted a retrospective multicenter study of 508 CM samples.
  
  
  METHODS
  All the dermoscopic images were analyzed to identify the dermoscopic criteria found in dermoscopically difficult melanomas (DDM) and to examine the possible relation of dermoscopic diagnosis with respect to the difficulty of the dermoscopic diagnosis and the melanoma thickness.
  
  
  RESULTS
  A significant percentage of melanomas, 89 of 508 (17.5%), were DDM. The criteria leading to a significant increased risk of DDM were presence of streaks [odds ratio (OR), 2.26; 95% confidence interval (CI), 1.15-4.47), absence or presence of regular pigmentation (OR, 3.41; 95% CI, 1.70-6.85), absence of a blue-whitish veil (OR, 4.04; 95% CI, 2.33-6.99), absence of regression structures (OR, 4.31; 95% CI, 2.42-7.66), and the presence of hypopigmentation (OR, 2.61; 95% CI, 1.49-4.58).
  
  
  CONCLUSIONS
  A significant number of melanomas defy even dermoscopic diagnosis. Only a meticulous comparative and interactive process based on an assessment of all the individual's other nevi ("ugly ducking" sign) and a knowledge about recent changes can lead to the recognition of DDM.
authors.affiliation: Centro di Riferimento Oncologico, CRO, Aviano, Italy. pizzichetta@cro.it
authors.forename: Maria A
authors.initials: MA
authors.lastname: Pizzichetta
authors.forename: Ignazio
authors.initials: I
authors.lastname: Stanganelli
authors.forename: Riccardo
authors.initials: R
authors.lastname: Bono
authors.forename: H Peter
authors.initials: HP
authors.lastname: Soyer
authors.forename: Serena
authors.initials: S
authors.lastname: Magi
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Canzonieri
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Lanzanova
authors.forename: Giorgio
authors.initials: G
authors.lastname: Annessi
authors.forename: Cesare
authors.initials: C
authors.lastname: Massone
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Cerroni
authors.forename: Renato
authors.initials: R
authors.lastname: Talamini
mesh_terms: D000328:Adult; D000368:Aged; D046169:Dermoscopy; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008545:Melanoma / Q000473:pathology*; D008875:Middle Aged; D009506:Nevus / Q000473:pathology; D015588:Observer Variation; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012878:Skin Neoplasms / Q000473:pathology*