Spider nevi go by many different names and they include spider angiomas or telangiectasias. When there is a single lesion it is called a spider nevus, when multiple- nevi.
Spider nevi are very superficial skin lesions and distinct from spider veins. They look very much like a spider with fine radiating lines. In fact, the dark center of a spider nevus receives a lot of blood and transmits it to the fine vessels in a radial fashion. When the center is compressed with a finger tip, the fine radiating lines disappear and when the compression is released, they reappear. This is what differentiates a spider nevi from a spider vein.
The center may vary in color-from red to purplish. In some cases the center spot may appear to be elevated and round.
How common are spider nevi?
They are variable in size ranging from 0.5 to 1 cm in diameter. Unlike a spider vein, spider nevi have a higher blood pressure and are much warmer to touch. They are seen in 10-15% of healthy adults and young children. The majority of lesions are not related to any disease.
What causes spider nevi?
Spider nevi are seen more often in pregnancy and in women who take the birth control pill. Amy condition which causes an increased level of the female sex hormone, estrogen, will also cause an increase in spider nevi. Since the liver breakdowns the female sex hormone (estrogen), any condition that damages the liver will cause an increase in the levels of estrogen (a damaged liver can't break down estrogen) and hence lead to increased spider nevi.
Liver conditions that are associated with spider nevi include:
- hepatitis B or C
- drug induced liver damage
- alcoholic cirrhosis (liver damage by alcohol)
Do spider nevi cause symptoms?
No, they are small skin lesions and contain a minute amount of blood. They do not cause any symptoms. When there are a few spider nevi, one should not worry. However, multiple spider nevi may be an indication of underlying liver problems.
Where do spider nevi commonly occur?
Spider nevi are usually seen in the upper part of the body, face, neck, upper chest and arms. Sometimes they may even occur inside the mouth or nose.
When they are associated with liver disease, they are commonly found on the hand and arms.
Are there any complications associated with spider nevi?
Since these lesions are very superficial and have fasting flowing blood at high pressures, any trauma can cause them to rupture. This may be associated with significant bruising and even bleeding.
Can they resolve spontaneously?
Yes, Spider nevi which develop during pregnancy usually resolve within 3-6 months after child birth. Nevi associated with birth control pills will also resolve when the pill is stopped.
How is the diagnosis of spider nevi made?
A simple physical examination will be adequate to make a diagnosis of spider nevi. When extremely large numbers of spider nevi are visible, the physician may order some blood work to ensure that the liver is functioning properly.
How are spider nevi treated?
Since these lesions cause no symptoms, there is no active treatment required.
The major reason for treating spider vein is cosmetic.
There are several methods to treat spider nevi which include:
Electrodessication (heating the nevus with an electrical wire)
Unlike spider veins, spider nevi respond poorly to treatment and scarring/darkening of the skin can occur. Since spider nevi can resolve on their own, the indications for treatment are questionable.
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