title: The ABCD rule of dermatoscopy. High prospective value in the diagnosis of doubtful melanocytic skin lesions.
abstract: BACKGROUND
  The difficulties in accurately assessing pigmented skin lesions are ever present in practice. The recently described ABCD rule of dermatoscopy (skin surface microscopy at x10 magnification), based on the criteria asymmetry (A), border (B), color (C), and differential structure (D), improved diagnostic accuracy when applied retrospectively to clinical slides.
  
  
  OBJECTIVE
  A study was designed to evaluate the prospective value of the ABCD rule of dermatoscopy in melanocytic lesions.
  
  
  METHODS
  In 172 melanocytic pigmented skin lesions, the criteria of the ABCD rule of dermatoscopy were analyzed with a semiquantitative scoring system before excision.
  
  
  RESULTS
  According to the retrospectively determined threshold, tumors with a score higher than 5.45 (64/69 melanomas [92.8%]) were classified as malignant, whereas lesions with a lower score were considered as benign (93/103 melanocytic nevi [90.3%]). Negative predictive value for melanoma (True-Negative divided by [True-Negative+False-Negative]) was 95.8%, whereas positive predictive value (True-Positive divided by [True-Positive+False-Positive]) was 85.3%. Diagnostic accuracy for melanoma (True-Positive divided by [True-Positive+False-Positive+False-Negative]) was 80.0%, compared with 64.4% by the naked eye. Melanoma showed a mean final dermatoscopy score of 6.79 (SD, +/- 0.92), significantly differing from melanocytic nevi (mean score, 4.27 +/- 0.99; p < 0.01, U test).
  
  
  CONCLUSIONS
  The ABCD rule can be easily learned and rapidly calculated, and has proven to be reliable. It should be routinely applied to all equivocal pigmented skin lesions to reach a more objective and reproducible diagnosis and to obtain this assessment preoperatively.
authors.affiliation: Department of Dermatology, University of Munich, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Nachbar
authors.forename: W
authors.initials: W
authors.lastname: Stolz
authors.forename: T
authors.initials: T
authors.lastname: Merkle
authors.forename: A B
authors.initials: AB
authors.lastname: Cognetta
authors.forename: T
authors.initials: T
authors.lastname: Vogt
authors.forename: M
authors.initials: M
authors.lastname: Landthaler
authors.forename: P
authors.initials: P
authors.lastname: Bilek
authors.forename: O
authors.initials: O
authors.lastname: Braun-Falco
authors.forename: G
authors.initials: G
authors.lastname: Plewig
mesh_terms: D003880:Dermatology / Q000379:methods; D005188:False Negative Reactions; D005189:False Positive Reactions; D006801:Humans; D008545:Melanoma / Q000473:pathology*; D009508:Nevus, Pigmented / Q000473:pathology*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012878:Skin Neoplasms / Q000473:pathology*