Linear and whorled nevoid hypermelanosis.

Linear and whorled nevoid hypermelanosis (LWNHM) is a reticulate pigmentary disorder with a sporadic occurrence, representing genetic mosaicism. It is characterised by hyperpigmented macules in a reticulate pattern along Blaschko's lines, sparing the mucous membranes and stabilising after one to two years. It may be associated with various neurological abnormalities. The disorder may resemble incontinentia pigmenti, epidermal nevus, or zebra-like hyperpigmentation clinically. We report LWMNHM in a 15-year-old girl with progressively increasing streaks of reticulate hyperpigmented macules arranged in a whorled pattern over the trunk and extremities, which appeared soon after birth. There was no history of any preceding eruption or any associated systemic abnormality. Histopathological examination revealed basal cell hyperpigmentation without any pigmentary incontinence. CT scan of the brain was normal.