The protective role of epidermal melanin in a patient with porphyria variegata and vitiligo.

To assess the role of epidermal melanin in a patient with porphyria variegata and vitiligo, the MED was determined in pigmented and vitiliginous skin for wavelengths of 310, 405 and 500 nm. The energy required to elicit erythema by irradiating vitiliginous skin at 310 nm was half that for pigmented skin. For 405 nm the differences was 4-fold and at 500 nm 2-fold. A possible explanation for the different protection by melanin against light of 310, 405 and 500 nm is given. UV-B irradiation, as a potent stimulus for melanization of the skin, is proposed as an additive measure in the protection against photosensitivity reactions in porphyria patients.