What are Venous Malformations?
(Normally, freshly-oxygenated blood pumped by the heart is delivered to various tissues by branching arteries. The blood then enters a fine network of tiny vessels called capillaries and nourishes the tissues. The “used” blood is passed back to the heart through the veins.) Venous malformations are collections of extra veins that are present since birth. These extra venous tissues cause purplish-blue compressible masses under the skin. The mass tends to become larger if it is below the level of the heart. The closer the mass is to the skin, the more clearly the purplish veins can be seen.
How are Venous Malformation diagnosed?
Venous malformations characteristically present as a painless purplish mass that is present since birth but may not be recognized. The mass grows slowly as the person ages. However, events such as surgery, trauma, infection, or hormonal changes associated with puberty, pregnancy, or menopause may cause it to expand rapidly. Occasionally, the mass can become swollen, tender, and discolored for a few days to weeks. This is usually caused by clotting of the slow moving blood within the venous malformation, which blocks the normal blood flow. Venous malformations can be confused with the more common hemangiomas or the less common arterio-venous malformations. The distinction can usually be determined by physical exam and patient history. The following is a general comparison between the three vascular anomalies:
Venous Malformation
Hemangiomas
Arterio-venous Malformations
Present at birth
Grow slowly with the child
Not present at birth
Undergo rapid growth
Present at birth, but usually not recognized.
Slowly increase in size over time or with trauma or puterty.
Soft, cool purplish compressible mass that is bigger when below the level of the heart
Firm, warm, reddish purple mass
Firm, warm pulsating mass
Can cause pain or other problems due to mass effect
Cause transient discomfort
Cause problems by bleeding, tissue ischemia and heart problems
Usually do not require treatment
Usually resolve without treatment
Usually do require treatment
What happens to Venous Malformations?
Venous malformations grow slowly over many years. Blood flows slowly in the malformed veins and they do not drain properly. Over time, these veins stretch and the venous malformation “grows”. They are almost always “benign” and do not require treatment.
What are the possible treatments?
Venous malformations do need to be treated if they cause pain, functional impairment, or severe cosmetic disfigurement. Medical treatments that are often effective include aspirin and supportive devices. Recurrent pain from clotting of the blood in the venous malformations can often be avoided by administering aspirin twice a week. If the malformation is on an extremity, an elastic stocking, glove, or sleeve can be used to slow its “growth” and to help with the discomfort.
Surgical treatment can be used to remove the mass of the venous malformation. Although surgery can be quite effective, it is often difficult to separate the venous malformation from the surrounding nerves and other important tissues. Therefore, it can be hard for the tissues to heal well their surrounding edges contain venous malformation that has not been successfully removed. An advantage of surgery is that very large areas can be treated at a single time.
Transcutaneous transvenous embolization, also called sclerotherapy, is a method that treats venous malformations by injection of a material that “burns” or hardens (scleroses) the venous malformation.
How is Sclerotherapy done?
A small needle is placed directly into the venous malformation. Radiographic contrast is injected into the lesion and monitored under fluoroscopy, a type of X-ray. This is called a venogram. After it is determined that the contrast does not go to any critical structures, ethanol is injected, again while monitoring under fluoroscopy. When this area of the lesion has been sufficiently treated, the skin overlying the lesion may appear darker in color. The treatment is terminated and another area is explored. Sclerotherapy is an in-patient procedure that requires general anesthesia.
How does Sclerotherapy work?
The injected ethanol gives a chemical burn to the inside of the blood vessel, which will be replaced by scar tissue as it heals. This process generally takes 3~4 weeks. The tissue surrounding the vein is also burned by the ethanol, but it usually heals normally over the next few weeks.
How will the area look after treatment?
Immediately after treatment, the area will be swollen three or four times larger than its previously untreated size. The skin will be tight, blistered, and discolored. In short, it will look like a burn. There will be little discomfort because the ethanol tends to temporarily block the thin pain-carrying nerves of the area. The swelling will decrease slowly over the next few days. If the skin over the venous malformation is particularly thin, the skin may ulcer and breakdown. This will heal to a small scar. Occasionally, a motor nerve is damaged by the ethanol—this almost always heals over the next few days to months and returns to normal. The swelling will resolve 2~3 weeks after the treatment. After 3~5 weeks, the area will start to decrease below its original size and will continue to do so for 2~4 months, with some further reduction happening up to 12 months following treatment.
What are the risks and benefits of Sclerotherapy?
Sclerotherapy is highly effective in treating venous malformations. A few months after therapy, the size of the treated area will have been reduced by approximately 80%. There will be a marked reduction in the purplish color, and the uncomfortable sensation of fullness associated with the venous malformation will have been lessened.
Because ethanol causes a chemical burn, the area which can be treated, as well as how much ethanol can be used, are limited during a single treatment. Usually we are limited to giving 1 cc of ethanol for each kilogram of patient body weight (about 1 ounce per 60 lbs). For these reasons lesions larger than about an inch have to be treated in stages.
Sclerotherapy is a relatively safe procedure, but not completely without risks. Reactions to medications or anesthetic agents, though very rare, do happen. The ethanol-contrast mixture can hurt other tissues such as nerves or overlying skin, causing nerve weakness and scarring. If the ethanol were to travel back to the eye or the brain it could conceivably cause blindness or a stroke.
Post treatment instructions
The area will look extremely swollen and discolored after the treatment. The treated area should be kept elevated and clean. It may ooze like any other burn. Gentle washing of the area with mild soap and water will help keep it clean. Vegetable oil can be placed on the area afterward to help with the dryness that can develop.
Slight discomfort is expected, but the area should not hurt or be tender. The patient may have a low grade temp (99.9oF) but should not have a fever. The area should be maximally swollen the following morning and look better each day. If an area of the skin has been ulcerated, it will take weeks for it to fill in and slowly scar. If any of the above signs (pain, fever, or additional swelling) are present, the patient should call immediately, since it could signify that the area has become infected and treatment with antibiotic may be necessary.
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