Two Cases of Vitiligo Developed on the Persisting Dermal Melanocytosis: Is There a Difference between Epidermal Melanocytes and Dermal Melanocytes?

Vitiligo is one of the most common pigmentary skin disorders; it is characterized by circumscribed depigmented macules due to the destruction of melanocytes. Although the etiology of vitiligo has not been fully elucidated, multiple factors including autoimmune and oxidative stress have been implicated in the pathogenesis of vitiligo. In contrast, dermal melanocytosis is histologically characterized by the presence of dermal melanocytes. It has been described that there are ectopic dermal melanocytes, which have failed to reach their proper location. A literature search revealed very few reports of patients with vitiligo developing vitiligo within dermal melanocytosis. Here, we report two cases of patients with vitiligo that occurred at pre-existing sites of dermal pigmented lesions. The histopathology showed the loss of epidermal melanocytes in spite of the existence of melanocytes in the dermis. There was no significant infiltration of inflammatory cells in the dermis. These cases illustrate unknown environmental factors as well as heterogeneity.