Development of vitiligo within segmental nevus depigmentosus: A very rare presentation

Nevus depigmentosus (ND) is a congenital leukoderma that is, stable in its size and distribution and may present as isolated, segmental or systematized form. Segmental ND sometimes can pose a diagnostic difficulty with segmental vitiligo. Likewise, segmental vitiligo overlaps with the clinical features of ND to a greater degree. A 15-year-old boy presented with two distinct asymptomatic pigmentary lesions involving the right thigh. Based on the clinical features, Wood's lamp examination and histological features a diagnosis of vitiligo arising within the confines of segmental ND was entertained. Though there are reports of vitiligo coexistent with ND in two different sites, and development of lentigines within ND, vitiligo developing within the preexisting ND makes this case an interesting presentation.