A spider angioma or spider naevus is a type of telangiectasis found slightly beneath the skin surface, often containing a central red spot and reddish extensions which radiate outwards like a spider's web. They are common and may be benign, presenting in around 10–15% of healthy adults and young children. However, having more than three spider angiomas is likely to be abnormal and may be a sign of liver disease. It also suggests the probability of esophageal varices.
Signs and symptoms
Spider angiomas are found only in the distribution of the superior vena cava, and are thus commonly found on the face, neck, upper part of the trunk, and arms. They may also be present on the backs of the hands and fingers in young children.
Cause
Spider angiomas form due to failure of the sphincteric muscle surrounding a cutaneous arteriole. The central red dot is the dilated arteriole and the red "spider legs" are small capillaries carrying away the freely flowing blood. If momentary pressure is applied, it is possible to see the emptied capillaries refilling from the center. No other angiomas show this phenomenon. The dilation, in turn, is caused by increased estrogenlevels in the blood. Many pregnant women and women using hormonal contraception have spider angiomas, which is due to high estrogen levels in their blood. Individuals with significant liver disease also show many spider angiomas, as their liver cannot metabolize circulating estrogens, specifically estrone, which derives from the androgen androstenedione. About 33% of patients with cirrhosis have spider angiomas.
Diagnosis
Diagnosis is by clinical examination. Spider naevi are most commonly seen by general practitioners, or dermatologists. Whilst a lesion can be identified as a spider naevus, this is not a diagnosis in itself. The clinical picture should be indicative of whether there is underlying disease that should be investigated.
Treatment
Spider angiomas are asymptomatic and usually resolve spontaneously. This is common in the case of children, although they may take several years to disappear. If the spider angiomas are associated with pregnancy, they may resolve after childbirth. In women taking oral contraceptives, they may resolve after stopping these contraceptives. The spider angiomas associated with liver disease may resolve when liver function increases or when a liver transplant is performed. For spider angiomas on the face, techniques such as electrodesiccation and laser treatment can be used to remove the lesion. There is a small risk of a scar, however it usually leaves nothing. Spider angiomas can recur after treatment.
