Very small 1–3-mm pigmented macules over the bilateral thighs of this adult woman characteristic of urticaria pigmentosa. Usually asymptomatic. May be misdiagnosed as vasculitis.

There are many brownish-red macules and patches. The infant was irritable and had difficulty sleeping. Scratching lesions caused itching hives and flushing.

A typical solitary lesion. This brown oval plaque had been present for months. There were no symptoms. There was no family history of mastocytosis.