Spider Naevus

Synonyms include: naevus araneus ,naevus arachnoidius, spider angioma ,tache stellaire, étoile vasculaire.

Spider nevus is the name given to small angiomata which appear on the surface of the skin. They were first described in 1869 by the English physician Erasmus Wilson¹ who noted them on the skin of a publican. They are described as "spiders" due to their appearance, the central, ascending vessel resembling the body of a spider, with the finer radiating vessels looking like the legs of a spider.
Spider naevi may be an indication of underlying disease, but can also occur in healthy individuals or in response to pharmacological agents. It seems likely that spiders and palmar erythema in patients with liver disease are a manifestation of disturbed circulating sex hormone activity, such as an elevated oestradiol/free testosterone ratio or they may be a toxic result of alcohol when this is the cause of impaired liver function. Spider naevi are more common in patients with alcoholic liver disease than with other causes.² Substance P may also be involved in patients with non-alcoholic cirrhosis.³

• 15-20% of healthy individuals will have one or more spider naevi
• Multiple spider naevi are more indicative of underlying disease
• They are common in childhood are show an equal sex incidence
• Spider naevi may also develop in pregnancy, or when taking the oral contraceptive pill
• Just one, or a few spiders are more common in women
• There is probably no racial difference in prevalence but they are less obvious on darker skin.

Spider naevi are usually asymptomatic. Presentation is because of cosmetic effect, especially if they are on the face or possibly concern about the aetiology. They may rarely bleed with minor trauma.
They are small lesions with a number of tiny blood vessels radiating from them to resemble the legs of a spider. The centre is about 1mm in diameter and the whole lesion about 5 to 10mm across. Firm pressure with something small such as the end, not the nib, of a ball point pen, will cause it to blanche and when the pressure is released it will rapidly refill.
Lesions most frequently occur on the face, below the eyes, and over the cheekbones. Other common sites include the hands, forearms, and ears. Spider naevi may occur on the trunk, or on the scalp, neck, arms and hands. Almost all spider naevi occur on the upper part of the body and only 1% below the umbilicus. Traditional teaching is that they are restricted to areas drained by the superior vena cava, but this is disputed by William Bean, one of the great founders of hepatology.⁴ Although healthy individuals may have one or more lesions, the presence of large numbers suggest underlying disease. Look for other stigmata of liver disease.
Ask about drugs as these may cause liver damage. Ask about alcohol consumption.

Spider naevi may be differentiated from other lesions with a similar appearance by the fact that they blanch with pressure, and refill again from the centre outwards:

• Campbell de Morgan spots are bigger, red spots without vessels radiating and they tend to occur in older people
• Insect bites may have a central punctum and should soon resolve. They may itch.
• Telangiectasia are dilated small blood vessels. Rendu-Osler Weber syndrome is a condition in which multiple telangiectasia occur.
• Haemangioma is a larger red spot, often raised.

For most healthy young people with a single of just a few lesions, and especially children, no investigation is required.
Otherwise, assess liver function. Thyroid function tests may also be indicated as they can occur with thyrotoxicosis.

Spider naevi may be associated with any condition that results in increased circulating levels of oestrogen including:

• Pregnancy
• Alcoholic cirrhosis
• Hepatitic cirrhosis
• Hepato-pulmonary syndrome

Although Erasmus Wilson made the classic description of spider naevi, it was William Bean who studied them extensively and who noted the association with cirrhosis, especially of the alcoholic kind. He will also be remembered for his poetry on the subject of alcoholic cirrhosis, spider naevi and palmar erythema and it is worthy of repetition:

An older Miss Muffett
Decided to rough it
And lived upon whisky and gin.
Red hands and a spider
Developed outside her for
Such are the wages of sin.⁵

Usually no treatment is required and many will fade spontaneously or resolve as the underlying condition improves. Spider naevi may be treated with laser therapy⁶ or electrodessication if desired for cosmetic reasons.

Benign lesion tend to resolve spontaneously but may take a number of years to do so. If associated with pregnancy they tend to go about 6 or 7 months after delivery. They will also resolve some time after stopping oral contraceptives. If associated with liver disease, they may resolve if the liver disease improves.