Nevus anemicus is a congenital disorder characterized by macules of varying size and shape that are paler than the surrounding skin and cannot be made red by trauma, cold, or heat.

[3] Often the patches are difficult to see against the background color of the patient’s skin, but if sunburn develops, then the white area stands out prominently.

This blanching is a functional rather than a structural abnormality, presumed to be caused by local increased sensitivity to catecholamines.

[5] Although the cutaneous vasculature appears normal histologically, the blood vessels within the nevus do not respond to injection of vasodilators.

[8][9] In most people a nevus anemicus is on a covered area and so light in appearance that no treatment is needed.