title: Blue-black rule: a simple dermoscopic clue to recognize pigmented nodular melanoma.
abstract: BACKGROUND
  Dermoscopy improves melanoma recognition, but most criteria were described in the context of superficial spreading melanoma.
  
  
  OBJECTIVE
  To test whether pigmented nodular melanoma could be recognized dermoscopically by the presence of a combination of blue and black colour within the lesion.
  
  
  METHODS
  Dermoscopic images of histopathologically diagnosed pigmented nodular tumours with no (or only minimal) flat component were evaluated for the presence of standard melanoma criteria and for the presence of a new feature named blue-black (BB) colour. Sensitivity, specificity, positive predictive value and negative predictive value were calculated for standard criteria and BB feature in relation to the diagnosis of melanoma and to diagnosis of malignancy.
  
  
  RESULTS
  Of 283 lesions, 160 were malignant, including 78 (27·6%) melanomas, and 123 were benign. The BB feature and the standard criteria had 78·2% and 43·6% sensitivity for melanoma, respectively, whereas a combined method based on the presence of either the BB feature or one (or more) of the standard criteria reached 84·6% sensitivity, with 80·5% specificity and 93·2% negative predictive value. Sensitivity values for malignant lesions were only 24·4%, 56·9% and 60% for standard criteria, BB feature and the combined method, respectively. However, the combined method gave 91·9% specificity and 90·6% positive predictive value for malignancy.
  
  
  CONCLUSIONS
  Using a method based on the BB feature or one of the standard melanoma criteria, only 9·4% of positive pigmented nodular lesions were found to be benign and only 6·8% of negative lesions were found to be melanoma histopathologically.
authors.affiliation: Dermatology Unit, Medical Department, Arcispedale Santa Maria Nuova, Viale Risorgimento 80, 42100 Reggio Emilia, Italy. g.argenziano@gmail.com
authors.forename: G
authors.initials: G
authors.lastname: Argenziano
authors.forename: C
authors.initials: C
authors.lastname: Longo
authors.forename: A
authors.initials: A
authors.lastname: Cameron
authors.forename: S
authors.initials: S
authors.lastname: Cavicchini
authors.forename: J-Y
authors.initials: JY
authors.lastname: Gourhant
authors.forename: A
authors.initials: A
authors.lastname: Lallas
authors.forename: I
authors.initials: I
authors.lastname: McColl
authors.forename: C
authors.initials: C
authors.lastname: Rosendahl
authors.forename: L
authors.initials: L
authors.lastname: Thomas
authors.forename: D
authors.initials: D
authors.lastname: Tiodorovic-Zivkovic
authors.forename: P
authors.initials: P
authors.lastname: Zaballos
authors.forename: I
authors.initials: I
authors.lastname: Zalaudek
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D003116:Color; D046169:Dermoscopy / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009508:Nevus, Pigmented / Q000473:pathology*; D012680:Sensitivity and Specificity; D012878:Skin Neoplasms / Q000473:pathology*; D055815:Young Adult