Vitiligo: is it grace or curse?

Vitiligo is a common skin disease, affecting approximately 0.5% of the general population. It is characterized by milky white macules and patches, which are a psychological burden to many patients. Although this disease has been known for a long time, the etiology is still under debate. Since melanin is a unique light absorbing and ultraviolet filtering pigment, it is generally accepted that its main function resides in the protection of skin cells against the deleterious effect of ultraviolet rays (UVRs). The occurrence of skin cancer in long lasting vitiligo is rare despite multiple evidence of DNA damage. The aim of this study was the immunohistochemical detection of p53 and Mdm2 in depigmented and "normal" pigmented skin of vitiligo patients to demonstrate the possible role of these proteins in the protection of vitiligo patients against actinic damage and non-melanoma skin cancer. Using standard immunohistochemical techniques, we examined 34 patients with vitiligo and 30 age- and sex-matched patients with noduloulcerative basal cell carcinoma as a control group. Both patients and control subjects had outdoor occupations. Skin biopsies were obtained from each case (from depigmented and "normal" pigmented UVR-exposed skin) and control subjects (from perilesional healthy skin). Both p53 and Mdm2 were strongly expressed in depigmented as well as "normal" pigmented skin of vitiligo patients. This expression involved the epidermis, skin adnexa and blood vessels, with significant differences between cases and controls. Both proteins showed nuclear and nucleo-cytoplasmic pattern of expression. Intense p53 and Mdm2 expression was in favor of generalized vitiligo. These results suggested that the over-expression of p53 and Mdm2 proteins in both depigmented and "normal" pigmented skin of patients with vitiligo could contribute to the decreased occurrence of actinic damage and non-melanoma skin cancer in these patients.