UVB 311 nm Tolerance of Vitiligo Skin Increases with Skin Photo Type

Abstract

It is assumed that skin is protected against sunburn by melanin. In patients with vitiligo, there are white patches in the normal pigmented skin. We noticed that there is a difference in burning capacity of these white patches between people with different skin types. With UVB 311 nm lamps, we irradiated both lesional and non-lesional skin with increasing doses in 33 patients with vitiligo, divided into 5 groups according to skin type (II-VI). Twenty-four hours later we assessed the minimal erythema dose and found a correlation between skin type and UV sensitivity in both lesional skin and normal skin. We suggest that there must be a protection mechanism, other than that offered by melanin pigmentation. The antioxidant status may play a role in this phenomenon.

Exploring the gaps in the evidence‐based application of narrowbandUVBfor the treatment of vitiligo

“…The result was a highly significant, linear trend correlating the average MED value to the patient's phototype suggesting that patients with a darker skin type can tolerate higher doses of UVB. In addition, the MED value measured for affected skin was found, on average, to be only 35% lower than unaffected skin . These findings are supported by a subsequent study in which the average MED in affected areas was only 22.9–25.1% lower than normal skin.…”

Anti‐oxidant defence mechanism in vitiliginous skin increases with skin type

“…However, cutaneous melanin has a low Sun Protection Factor (SPF), as demonstrated by the SPF 2 estimated in vitiligo patients with skin type III 46 and by the fact that transmission of shortwave UV is only 4–6 times more when the epidermal sheets were derived from dark skin as compared with the light skin 47 . We previously noticed that in depigmented vitiligo skin the (sub)erythematogenic UV doses correlated with skin type of the patients, 4 suggesting that melanin is not the only responsible for UV sensitivity. Thus, the relationship between pigmentation and photoprotection should be far more complex than assumed.…”

The impact of skin colour on human photobiological responses

“…Indeed, one study comparing MED on vitiligo lesions and adjacent non‐lesional skin of SPT II ‐ VI patients found a maximal difference of about 3 between the two sites. However, the authors also noted a similar ~2.5‐fold skin type‐dependent difference in the MED in the lesional skin which suggests that factors other than melanin content may be important (Caron‐Schreinemachers et al., ). Overall, these data suggest that melanin has only a relatively modest effect on MED.…”