irAE-induced vitiligo
ICI-induced vitiligo; checkpoint-inhibitor vitiligo; melanoma-associated leukoderma
Patchy depigmentation — clinically indistinguishable from idiopathic vitiligo — develops in 5–25% of melanoma patients on anti-PD-1 / anti-CTLA-4 immunotherapy. It is a specific marker of an active anti-melanoma T-cell response and is associated with significantly better progression-free and overall survival in melanoma cohorts. It is not seen with the same frequency in non-melanoma cancers treated with the same drugs. Management is cosmetic only — there is no clinical indication to suppress the immune response that is driving it; photoprotection of depigmented skin is essential.
Clinical features
- Patchy, symmetric, well-demarcated depigmentation on sun-exposed sites (face, neck, dorsal hands, extensor limbs); occasionally generalised.
- Wood's-lamp examination confirms melanocyte loss.
- Develops typically 3–12 months after starting ICI — later than the typical maculopapular irAE.
- Not usually preceded by inflammation or pruritus.
- Frequency — 5–25% of melanoma patients; the wide range reflects active surveillance practice and trial population.
Biology and biomarker role
- ICI-induced vitiligo reflects activated T-cell recognition of shared melanocyte antigens (Melan-A / MART-1, gp100, tyrosinase) on both melanoma cells and normal melanocytes.
- Multiple cohort studies (e.g. Hua, JAMA Dermatol 2016) — vitiligo onset associated with significantly improved PFS and OS in metastatic melanoma.
- The same effect is not observed with the same frequency in cancers without melanocyte antigen expression (e.g. NSCLC).
- Vitiligo is now recognised as a clinical correlate of immunotherapy response, not just a side effect.
Management
- Do not suppress the immune response. Vitiligo is a marker of effective melanoma immunity; topical or systemic immunosuppression to reverse it is not indicated and risks compromising anti-tumour activity.
- Cosmetic options — camouflage make-up (Veil, Dermablend), self-tanning lotions, fake-tan products.
- Photoprotection of depigmented skin is essential — SPF 50+, hat, sun-avoidance — to prevent UV damage of unprotected areas.
- Counsel patients about the favourable prognostic implication — vitiligo is a "good news" sign rather than a complication.
- Repigmentation is rare; for distress, refer to specialist vitiligo clinic for narrow-band UVB or other modalities — note immunosuppressive therapy is not appropriate.
Differential diagnosis
- Idiopathic vitiligo — particularly relevant in patients with no prior history of pigmentary change.
- Pityriasis versicolor — distribution and scale on the back; KOH scraping diagnostic.
- Post-inflammatory hypopigmentation — preceded by eczema, dermatitis or trauma.
- Halo phenomenon around a previous naevus or regressing melanoma.
References
- Hua C et al. Association of vitiligo with tumor response in patients with metastatic melanoma treated with pembrolizumab. JAMA Dermatol; 2016.
- Nakamura Y et al. Correlation between vitiligo occurrence and clinical benefit in advanced melanoma patients treated with nivolumab. J Dermatol Sci; 2017.
- Babai S et al. Cutaneous adverse events of immune checkpoint inhibitors. Br J Dermatol; 2020.
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