A white spot since birth
The lesion on the patient’s chest was asymptomatic. But what caused it—and could it be a problem?
Diagnosis: Nevus anemicus
The patient had a nevus anemicus, which typically presents as an irregularly shaped hypopigmented patch on surrounding normal skin.1 Sometimes there are satellite macules, as well.2
Nevus anemicus is present at birth or appears shortly thereafter. It continues to grow with the child, and it remains asymptomatic. It is usually located on the trunk—primarily on the upper chest. However, there have been cases involving the extremities, head, and neck.3 The prevalence of this condition in the United States is unknown, but it is not considered rare. It is more common in females.4
Although nevus anemicus is an isolated finding in normal healthy individuals, it may occur in association with genodermatoses such as neurofibromatosis, and in conjunction with nevus flammeus and Mongolian spot in phakomatosis pigmentovascularis.1
Not a true nevus
This lesion is not a true nevus; rather, it is a congenital vascular anomaly with localized hypersensitivity to catecholamines. The vasoconstriction caused by this hypersensitivity results in skin pallor. When pressure is applied to the surrounding skin (diascopy), the border between the nevus and surrounding skin is lost due to blanching of surrounding skin.5
Intralesional injection of vasodilators, such as bradykinin, pilocarpine, acetylcholine, 5-hydroxytryptamine, nicotine, or histamine, fails to produce vasodilation in the affected areas.6 Axillary sympathetic block and intralesional injection of α-adrenergic blocking agents result in erythema.3 These findings support the conclusion that it is not a true nevus, but rather a vascular anomaly.
