title: Modified dermoscopic algorithm for the differentiation between melanocytic and nonmelanocytic skin tumors.
abstract: BACKGROUND
  The use of dermoscopy (dermatoscopy, epiluminescence microscopy, surface microscopy) improves the clinical diagnostic accuracy of skin tumors by applying different algorithms or scores. The first step in the dermoscopic evaluation is the differentiation between melanocytic and nonmelanocytic skin tumors.
  
  
  OBJECTIVE
  To evaluate the diagnostic accuracy of the established dermoscopic algorithm (EDA) and the modified dermoscopic algorithm (MDA) for melanocytic versus nonmelanocytic skin tumors.
  
  
  METHODS
  Two hundred forty-nine patients with melanocytic and nonmelanocytic skin lesions were included. Dermoscopic images of the tumors were taken with 10-fold magnification, followed by surgery and histopathology at the departments of Dermatology at the universities of Tuebingen, in Germany, and Naples, in Italy. Each lesion was classified using the EDA and MDA. In the MDA, accessory nipples and dermatofibromas were considered in particular.
  
  
  RESULTS
  With the EDA, 225 of 249 (90.4%) skin tumors were correctly classified in one of the six groups. With the MDA, 237 of 249 (95.2%) were correctly classified. Improvement was achieved in 12 (4.8%) better classified skin tumors. In both algorithms, no melanoma was classified as a nonmalignant melanocytic tumor. All melanomas were classified in the group of melanocytic tumors and one melanoma was classified in the group of basal cell carcinomas.
  
  
  CONCLUSIONS
  Both dermoscopic algorithms for the differentiation between melanocytic and nonmelanocytic skin tumors were simple and effective when applied step by step. The MDA is an improvement on the EDA with the classification of accessory nipples and dermatofibromas.
authors.affiliation: Private and Teaching Practice of Dermatology, Konstanz, Germany. a.blum@derma.de
authors.forename: Andreas
authors.initials: A
authors.lastname: Blum
authors.forename: Jennifer
authors.initials: J
authors.lastname: Clemens
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Argenziano
mesh_terms: D000465:Algorithms; D046169:Dermoscopy; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008545:Melanoma / Q000175:diagnosis* / Q000473:pathology; D012680:Sensitivity and Specificity; D012878:Skin Neoplasms / Q000175:diagnosis* / Q000473:pathology