title: Dermatoscopy of flat pigmented facial lesions.
abstract: BACKGROUND
  The diagnosis of flat pigmented lesions on the face is challenging because of the morphologic overlap of biologically different lesions and the unknown significance of dermatoscopic patterns.
  
  
  OBJECTIVE
  To better characterize dermatoscopic patterns of various types of flat pigmented facial lesions and to analyse their significance by calculating their relative risks and diagnostic values.
  
  
  METHODS
  We prospectively analysed dermatoscopic images of 240 flat pigmented facial skin lesions collected consecutively from 195 patients (41.5% females, mean age: 61 ± 14 years) between 2007 and March 2012 in a primary skin cancer practice situated in Queensland, Australia.
  
  
  RESULTS
  Histopathologically 114 (47.5%) lesions were malignant (24 lentigo maligna, 21 basal cell carcinomas and 69 pigmented actinic keratoses). Compared with all other patterns the positive predictive value for lentigo maligna was highest for a pattern of circles (31.3%, 95% CI: 11.1-58.6%). A pattern of clods was associated with basal cell carcinoma. If grey structures were present the relative risk for malignancy was 2.2 (95%CI: 1.4-3.4). The best clues to differentiate pigmented actinic keratosis from other lesions were the presence of scale (positive predictive value: 72.2%, specificity: 94.2%), white circles (positive predictive value: 68.8%, specificity: 94.2%) and a sharply demarcated border (positive predictive value: 44.2%, specificity: 86.0%).
  
  
  CONCLUSIONS
  In flat lesions a pattern of circles bears the highest risk for facial melanoma but other patterns do not exclude it. Scale, white circles and a sharply demarcated border are clues to pigmented actinic keratoses. The presence of grey colour is a clue to malignancy regardless of pattern.
authors.affiliation: Department of Dermatology, Division of General Dermatology, Medical University of Vienna, Vienna, Austria.
authors.forename: P
authors.initials: P
authors.lastname: Tschandl
authors.forename: C
authors.initials: C
authors.lastname: Rosendahl
authors.forename: H
authors.initials: H
authors.lastname: Kittler
mesh_terms: D000328:Adult; D000368:Aged; D002280:Basal Cell Carcinoma / Q000473:pathology*; D046169:Dermoscopy; D003937:Diagnosis, Differential; D005148:Facial Dermatoses / Q000473:pathology*; D005153:Facial Neoplasms / Q000473:pathology*; D005260:Female; D006801:Humans; D018327:Hutchinson's Melanotic Freckle / Q000473:pathology*; D055623:Keratosis, Actinic / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012878:Skin Neoplasms / Q000473:pathology*