Butterfly-shaped mark: a variant form of nevus flammeus simplex

A red-violet, rhomboid-shaped mark on the sacrum of 25 children is described. It is recognized, for the first time, as a part of the nevus flammeus simplex distribution; it is less common than the erythema nuchae or the facial salmon patch. It has the tendency to disappear more slowly than other forms of nevus flammeus simplex. No further investigations seem indicated.