title: Dermoscopic examination of nail pigmentation.
abstract: BACKGROUND
  Diagnosis of longitudinal melanonychia is usually difficult, and neither a single clinical criterion nor a combination of symptoms currently can be used to clearly distinguish malignant from benign bandlike pigmented nail lesions. Biopsy is painful and often leaves definitive dystrophic scars.
  
  
  OBJECTIVE
  To describe and evaluate dermoscopic patterns associated with longitudinal nail pigmentation.
  
  
  METHODS
  A total of 148 unselected consecutive cases of longitudinal melanonychia were included over a period of 4 years (20 melanoma, 37 nevi, 16 drug-induced nail pigmentation, 45 nail apparatus lentigo of various types, 8 ethnic-type nail pigmentation, and 22 subungual hemorrhages). All patients were recruited from the dermatology unit outpatient clinic of the Hôtel Dieu de Lyon. All cases were photographed in vivo under oil immersion (dermoscopy). Patterns were recorded prior to final pathologic diagnosis. An independent biostatistics unit performed statistical evaluation using 7 semiologic patterns.
  
  
  RESULTS
  Melanoma cases were significantly associated with a brown coloration of the background and the presence of irregular longitudinal lines (P =.001). Blood spots were mostly observed in subungual hemorrhages (P =.001); however, their presence could not rule out melanoma. Micro-Hutchinson sign was observed only in melanoma, but its rare occurrence did not allow any statistical evaluation of its specificity. Nail apparatus nevi were significantly associated with a brown coloration of the background and the presence of regular lines (P =.001). Nail apparatus lentigo, ethnic-type pigmentation, and drug-induced pigmentation were significantly associated with homogeneous longitudinal thin gray lines and gray coloration of the background (P =.001). Microscopic longitudinal grooves were unspecific, occurred in several conditions, and were associated with any type of ungual discoloration.
  
  
  CONCLUSIONS
  We believe that dermoscopic examination of the nail plate in cases of longitudinal melanonychia provides useful information that could help clinicians to more accurately decide if a nail apparatus biopsy should be performed; however, histopathologic diagnosis remains the gold standard in doubtful cases.
authors.affiliation: Dermatology Unit, Hôtel Dieu de Lyon, 69288 Lyon CEDEX 02, France.
authors.forename: Sandra
authors.initials: S
authors.lastname: Ronger
authors.forename: Sandrine
authors.initials: S
authors.lastname: Touzet
authors.forename: Claire
authors.initials: C
authors.lastname: Ligeron
authors.forename: Brigitte
authors.initials: B
authors.lastname: Balme
authors.forename: Anne Marie
authors.initials: AM
authors.lastname: Viallard
authors.forename: Danièle
authors.initials: D
authors.lastname: Barrut
authors.forename: Cyrille
authors.initials: C
authors.lastname: Colin
authors.forename: Luc
authors.initials: L
authors.lastname: Thomas
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D003880:Dermatology / Q000295:instrumentation / Q000379:methods*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008545:Melanoma / Q000453:epidemiology / Q000473:pathology*; D008548:Melanosis / Q000175:diagnosis / Q000453:epidemiology / Q000473:pathology*; D008875:Middle Aged; D009260:Nail Diseases / Q000175:diagnosis* / Q000453:epidemiology; D011336:Probability; D012307:Risk Factors; D012680:Sensitivity and Specificity; D012878:Skin Neoplasms / Q000453:epidemiology / Q000473:pathology*