Vitiligo Diagnosis: Wood’s Lamp, Dermoscopy, and Differential Workup

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Key Takeaways

  • Wood’s lamp: vitiligo shows bright chalk-white fluorescence with sharp borders; early lesions highlight margins before clinical contrast is obvious.
  • Dermoscopy: perifollicular pigment “islands,” starburst/feathery borders, and pigment network loss support activity and predict repigmentation potential.
  • Biopsy: rarely required; reserve for atypical/segmental cases, inflammatory rims, or to exclude mimickers (fungal, lichenoid, neoplastic).
  • Differential: tinea versicolor (yellow-green fluorescence, scale), pityriasis alba (ill-defined hypopigmentation), post-inflammatory change, chemical leukoderma, nevus depigmentosus.

Wood’s Lamp Findings

Table 1. Typical UV-A (365 nm) patterns.
Condition Wood’s lamp appearance Notes
Vitiligo (nonsegmental) Bright, chalk-white accentuation; sharp borders Early lesions highlight rims > center
Tinea versicolor Yellow-green or coppery fluorescence Fine scale; KOH positive
Pityriasis alba Mild accentuation; ill-defined No bright fluorescence
Nevus depigmentosus Off-white, stable borders from childhood Non-progressive
Chemical leukoderma Depigmentation at exposure sites History of phenols/catechols

Dermoscopy

Table 2. Dermoscopic signs that support vitiligo.
Feature Interpretation Clinical note
Perifollicular pigment “islands” Repigmentation potential Track during therapy (F-VASI)
Starburst/feathery borders Activity at margins Targets for excimer/NB-UVB
Absent pigment network Melanocyte loss Helps distinguish from PIH
Inflammatory rim (rare) Active halo Consider biopsy if atypical

Differential Diagnosis

Table 3. Quick differential for hypo/depigmented patches.
Entity Clues Tests
Tinea versicolor Fine scale, truncal distribution KOH prep; Wood’s yellow-green
Pityriasis alba Children, atopy, ill-defined Clinical; emollients improve
Post-inflammatory hypopigmentation History of rash/trauma Review photos/history
Nevus depigmentosus Stable from childhood Dermoscopic network present
Chemical leukoderma Occupational/cosmetic exposure Patch test/history
Lichen sclerosus (genital) Porcelain plaques, pruritus Consider biopsy
Leprosy (rare locales) Sensory loss, nerve thickening Neurologic exam, smear/biopsy

When to Biopsy

  • Atypical distribution or rapid inflammatory change.
  • Segmental/linear lesions with diagnostic uncertainty.
  • To exclude mimickers (e.g., MF/CTCL in unusual patches).

Assessing Activity & Baseline

  • Document F-VASI/T-VASI, anatomic zones, and photo baselines under standardized light.
  • Use Wood’s lamp to map subclinical margins for targeted therapy (excimer, topical immunomodulators).
  • Note Koebner sites (friction/trauma) for counseling and protection.

References

  1. Clinical guidelines on vitiligo diagnosis using Wood’s lamp and dermoscopy.
  2. Differential diagnosis reviews for hypopigmented and depigmented dermatoses.
  3. Studies correlating dermoscopic signs with repigmentation and VASI endpoints.
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