Background: Nevus is a hamartoma or malformation of one or more skin components, resulting in aberrant differentiation of the cell lineage(s) mostly during developmental stages. Although multiple lineages may be involved in a nevus, the combination of melanocyte and keratinocyte abnormalities has been rarely discussed.
Objectives: To present two cases of congenital nevi with hypomelanosis and superficial fine scales.
Materials & methods: Skin specimens of the patients were analysed by immunohistochemistry and electron microscopy.
Results: Morphological and immunohistochemical studies indicated aberrant epidermal differentiation in the lesional skin specimens. Electron microscopy showed defective melanosome maturation in the melanocytes of the nevi samples.
Conclusion: These results demonstrate that both epidermal and melanocytic lineages can concomitantly contribute to the formation of a nevus lesion.
Keywords: epidermal differentiation; epidermal nevus; filaggrin; keratin; melanosome; nevus depigmentosus.