Familial progressive hypermelanosis in Indian monozygotic twins.

Familial hyperpigmentation, or melanosis universalis hereditaria, is a rare hyperpigmentary disorder with onset in infancy. Here, we describe monozygotic twins with similar pattern of progressive hyperpigmentation with onset in early neonatal period without any family history. Histopathological examination showed increased melanin throughout the epidermis. Although hereditary defects may influence melanogenesis resulting in a pigmentary anomaly, the pathogenesis of hyperpigmentation in this case remains unclear.