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VASCULAR STEAL

White avascular spots

White, avascular macules approximately 5mm in size (Fig.15.61) may occasionally be seen on the arms and legs of white people, usually in children or in women. Occasionally, they are numerous enough to prompt a patient to seek medical attention. The white macules are due to decreased blood content, probably secondary to local arteriolar vasoconstriction. There is often a centrally placed prominent red arteriole if the lesions are examined carefully. Compression of this restores the normal color (by contrast to idiopathic guttate hypomelanosis, which is unaffected by pressure). No treatment is needed or known to be effective.

Nevus anemicus

The white appearance of the nevus anemicus results from a paucity of blood within the lesion, secondary to permanent vasoconstriction. This vasoconstriction is a result of hyperreactivity to normal levels of circulating catecholamines. Vitiligo may look similar, but is whiter than nevus anemicus, and the edges cannot be obliterated with pressure. In addition, Wood's light accentuates vitiligo but makes the nevus anemicus invisible (as the epidermal pigment is normal).

    This uncommon, congenital, white patch occurs most commonly on the trunk. The border is irregular and sharply demarcated, but can be obliterated by blanching the surrounding skin (Fig.15.62). It seems to be more common in females and may be seen in association with a PWS.

    There is no known effective treatment.

Figure 15.62 Nevus anemicus. The edges can be obliterated with pressure, verifying that this white lesion is caused by decreased blood content, not decreased pigment.

Figure 15.63 Acute radiation dermatitis. The skin is red and inflamed in this radiation port.

White/Cox: Diseases of the Skin, 2ed.(c) 2006, Elsevier Inc. All rights reserved.