Linear and whorled naevoid hypermelanosis on an infants leg. This rare condition first presents within a few weeks of birth with areas of hyperpigmentation on the skin that are distributed along the lines of Blaschko, pathways of epidermal cell migration during foetal development. The hyperpigmentation progresses for one to two years before stabilising. The cause is not known. Treatment is not necessary, but the areas of hyperpigmentation may be lightened with laser therapy, chemical peels or depigmentation creams.