Nevus depigmentosus is a congenital disorder characterised by localised loss of skin pigmentation and can be readily distinguished from vitiligo. Although age is not a major factor in its development, approximately 19% of cases are present at birth. The lesions may increase in size proportionally with the growth of the body, but their distribution remains stable, and they are non-progressive hypopigmented patches. The exact cause of nevus depigmentosus is not fully understood; however, a sporadic defect in embryonic development has been proposed as a possible etiological factor.
Signs and symptoms
Nevus depigmentosus presents as localized white patches on the skin that may occur on any area of the body. These legions are typically stable over time. Individual lesions are permanent, and there are currently no effective therapies to restore pigmentation in the affected areas. When hair is present within a lesion, it is usually colourless or white. ==Causes==
Causes
In nevus depigmentosus, melanocytes, melanosomes, and the process of melanogenesis are normal; however, the defect lies in the impaired transfer of melanosomes to keratinocytes. ==Diagnosis==
Diagnosis
An initial diagnosis is typically made based on the characteristic appearance of the hypopigmented patches and their stable distribution. The diagnosis may be confirmed with a skin biopsy, although this is not always required. ==Treatment==
Treatment
Various therapeutic modalities have been attempted to repigment the lesions of nevus depigmentosus, including psoralen plus ultraviolet A (PUVA) therapy, excimer laser treatment, and different grafting techniques. PUVA therapy has not been shown to be beneficial. Successful repigmentation has been reported in a single case following 14 sessions of excimer laser treatment. Though repigmentation of nevus depigmentosus may be achieved through grafting techniques, the outcomes are inconsistent, and recurrence can occur. Based on the experience reported, both the quality of repigmentation and long-term pigment retention are unpredictable. ==See also==