Spider nevus goes by several names:
- spider veins
- spider angioma
- nevus araneus
- vascular spider
A spider nevus is a collection of small, dilated arterioles (blood vessels) clustered very close to the surface of the skin. The cluster of vessels is web-like, with a central spot and radiating vessels.
Spider nevi (plural) can be caused by injuries, sun exposure, hormonal changes, or liver disease, but often the cause is unknown. For most people, the nevi are not a medical concern. In some cases, they cause discomfort. The vessel clusters can be treated or removed in a number of ways, which include the use of compression stockings, chemical injections, and laser treatments.
For most people with spider nevus, the only symptom is the appearance of the vessel cluster. There may be a red dot in the center of a cluster of thin vessels, but this is not always the case. The thin vessels form a web-like shape and are red, blue, or purple in color. When you apply pressure, they will disappear and then reappear because blood is flowing back into the vessels.
Spider nevi can occur anywhere on the body, but are most common on the face, neck, and legs (sun-exposed areas). Some people may experience aching or burning in the area of the vessel cluster. This pain occurs most commonly when the vessels are in the legs, and after a long period of standing.
Spider nevi are usually not cause for concern if you don’t have any other symptoms or health conditions.
If you have a spider nevus and feel weak, unusually tired, or bloated, or if your skin or eyes appear yellow, you should see your doctor. You should also see your doctor if you have multiple clusters of spider vessels, to find out if you have underlying liver problems. If you do not have any symptoms of illness, you can wait until your regular checkup to show the nevus to your doctor.
The webs of small arterioles and capillaries that appear close to the skin are abnormal.
What causes this to happen is not entirely understood. Researchers believe that various factors may result in spider nevi. These factors include:
- exposure to the sun
- changes in hormone levels
- underlying illnesses, such as liver disease
Spider nevi, especially if there is more than one, is a common sign of liver disease. People with liver disease often have multiple vessel clusters at a time.
Spider nevus commonly occurs when you have a lot of estrogen in your system, as is the case with chronic liver disease or during pregnancy. Spider nevus is more common in people with alcohol-related liver cirrhosis (liver disease) than in those with cirrhosis not related to alcohol.
Although the causes of spider nevus are not fully understood, several factors put you at a higher risk:
- Age: The older you are, the more likely you are to get spider nevi. Aging may cause the valves in your blood vessels to weaken.
- Hormonal changes: Going through puberty, pregnancy, and menopause, as well as taking hormonal contraceptives, may lead to spider nevi.
- Sun exposure: Being in the sun, especially if you are fair-skinned, can cause spider nevi to form on your face.
- Family history: Weak vessel valves may run in families, so if members of your family have spider nevi, you are more likely to get them as well.
- Obesity: Excess weight can put pressure on your blood vessels.
- Sitting or standing for long periods of time: Being immobile can prevent the healthy circulation of blood.
Your doctor will most likely be able to tell you if you have spider nevi simply by looking at the appearance of the skin in question. Sometimes a skin biopsy may need to be performed to confirm the diagnosis. What is more important, however, is diagnosing the underlying cause and ruling out certain conditions that may have produced the vessel clusters.
You will be asked about hormone supplements and any other medications you are taking. Your doctor will also ask you about alcohol consumption because alcohol abuse can lead to liver disease. Spider nevi may be a sign of liver disease. If liver problems are suspected, your doctor may draw a sample of your blood to be tested.
The liver is responsible for many important tasks, such as detoxifying the blood, helping to digest food, and producing proteins that help the blood to clot. Liver disease testing, also called a liver panel, involves taking blood samples to test for the enzymes and proteins produced and excreted by the liver. Increased or decreased levels of these substances, as well as the presence of certain types, can signal liver disease.
In many cases, there is no need for spider nevi to be treated. If they are not causing uncomfortable burning or itching and are not related to liver disease, then spider vessels are not harmful. If, however, they cause discomfort, or if you choose to have them treated for cosmetic purposes, you have several choices.
Lasers aimed at the spider nevus can eventually cause it to fade and disappear. The laser and the heat it emits may cause some pain or discomfort, but this should go away as soon as the laser is removed. Two to five treatments are typically needed to completely fade the spider nevus.
You may not be able to prevent spider nevus entirely. If you are predisposed to this condition due to family history and genetics, you’re likely to get spider nevi no matter what you do. While no specific preventive measures are known, you may prevent new spider nevi from forming by:
- avoiding hormone therapy
- wearing sunscreen on those areas most commonly affected, including the face, neck, and legs
- controlling your alcohol consumption
- treating liver disease if present