title: The significance of blue color in dermatoscopy.
abstract: OBJECTIVE
  Skin lesions with blue color are frequently excised to rule out malignancy. The objective of the present study was to investigate the significance of blue color.
  
  
  METHODS
  We retrospectively scanned dermatoscopic images for blue color and classified them according to pattern analysis.
  
  
  RESULTS
  Of 1,123 pigmented skin lesions, 144 (12.8 %) showed blue color, 92 of which (63.9 %) were malignant. Among lesions with blue color, the most common benign diagnoses were nevi (n = 35, 24.3 %) and seborrheic keratoses (n = 8, 5.6 %). Of 103 (71.5 %) lesions with a structureless blue pattern, eight (7.8 %) were entirely blue and 95 (92.2 %) were partly blue, of which 81 (78.6 %) showed peripheral or patchy and 14 (13.6 %) central blue color. Most lesions with peripheral or patchy blue color were melanomas (n = 47, 58 %), whereas most lesions with central blue color were nevi (n = 9, 64.3 %). Of 28 lesions with blue clods, 17 (60.7 %) were basal cell carcinomas. With respect to malignancy, the positive predictive value of blue color was 63.9 % (95 % CI: 56.0-71.8 %).
  
  
  CONCLUSIONS
  Among malignant lesions with blue color, structureless peripheral or patchy blue color is a clue for melanoma, while blue clods point to basal cell carcinoma. Pitfalls include seborrheic keratoses, which may show blue color, as well as some nevi, especially combined nevi.
authors.affiliation: Department of Dermatovenereology, Medical University of Belgrade, Clinic of Dermatovenereology, Clinical Center of Serbia, Belgrade, Serbia.
authors.forename: Mirjana
authors.initials: M
authors.lastname: Popadić
authors.affiliation: Department of Dermatology, Division of General Dermatology, Medical University of Vienna, Austria.
authors.forename: Christoph
authors.initials: C
authors.lastname: Sinz
authors.affiliation: Department of Dermatology, Division of General Dermatology, Medical University of Vienna, Austria.
authors.forename: Harald
authors.initials: H
authors.lastname: Kittler
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002280:Basal Cell Carcinoma / Q000473:pathology*; D002648:Child; D003116:Color; D003124:Colorimetry / Q000379:methods; D046169:Dermoscopy / Q000379:methods*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D017492:Keratosis, Seborrheic / Q000473:pathology*; D008297:Male; D008545:Melanoma / Q000473:pathology*; D008875:Middle Aged; D018329:Nevus, Blue / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012878:Skin Neoplasms / Q000473:pathology*; D055815:Young Adult
keywords: blue color; dermatoscopy; dermoscopy