What are vascular malformations?
Vascular malformations form when the channels that carry blood or lymph do not develop properly before birth. Unlike hemangiomas, they usually grow as a child grows, and they don’t go away without treatment. They affect boys as often as girls, and most are obvious at birth, although some remain undetected until adolescence or even adulthood.
What are the main types of vascular malformations?
Capillary malformation (CM) is a common vascular birthmark also known as a “port-wine” stain because of the pink/red/purple discoloration of the skin. It consists of small blood vessels, called capillaries, in the skin. They usually occur on the face, but may appear elsewhere on the body, and often become darker with age. Since they don’t reach very deeply below the surface of the skin, CM can often be effectively treated by laser photocoagulation.
Lymphatic malformation (LM) is an abnormality of lymph vessels. (The older terms are cystic hygroma and lymphangioma.) Lymph is a clear-yellowish fluid that carries fats and proteins back to the bloodstream and helps remove bacteria from bodily tissues. Lymph vessels drain fluid from parts of the body that become swollen during an infection. If these vessels are malformed at birth, they form large, soft masses, usually in the head and neck, armpit, or groin area. The most common problem associated with lymphatic malformations is infection. Most such infections are minor and go away after antibiotic treatment. In more serious cases, the child must stay in the hospital to receive antibiotics intravenously (directly in a vein). Another potential problem is bleeding into a lymphatic malformation, which can cause pain and swelling, but usually not fever.
Arteriovenous malformation (AVM) is a fast-flow anomaly (because it involves abnormal arteries) composed of abnormal connections between arteries and veins. AVMs cause pain, skin breakdown, overgrowth of tissue, and even congestive heart failure. AVMs can expand, often requiring embolization (a procedure in which inert material is injected into the vessels to block them) or sclerotherapy (when the injection is directly into the AVM), followed by surgical treatment.
Venous malformation (VM) is a slow-flow anomaly (because it involves veins) that consists of enlarged, sponge-like channels. Treatment may be required if the VM causes pain, distortion, obstruction, or bleeding.
Combined vascular malformations involve more than one type of vascular channel and tissue. Often these complex anomalies are associated with overgrowth of bone and soft tissues, usually in a limb or on the trunk of the body.
What causes vascular malformations?
Researchers believe they arise as a result of abnormal formation of blood or lymph vessels early in the life of the embryo. No food, medication, or activity during pregnancy is known to cause a vascular malformation. Sometimes vascular anomalies occur in families. Studies of these families have revealed mutated genes that cause CM, LM, VM, and AVM.
How are vascular malformations diagnosed?
A physical examination and medical history are usually sufficient to make the diagnosis. Often, however, ultrasonography, magnetic resonance imaging (MRI), or angiography is used to determine the extent of the vascular anomaly and plan the treatment.
What do the different types of vascular malformations look like?
CM: CM appears as flat, sharply demarcated, red-pink stains of the skin.
LM: LM in the skin presents as clear bubbles (vesicles) that often become dark red due to bleeding. It commonly occurs in the neck and armpit, but can arise anywhere and causes localized swelling and sometimes extensive enlargement of soft tissues (such as muscle and skin).
AVM: The blush of an AVM is sometimes mistaken in infants and children for a hemangioma. AVM becomes obvious as signs of fast-flow appear. The skin becomes darker red or purple, veins become prominent, a mass appears beneath the stain, and there is local warmth.
VM: VM is dark blue and usually soft, although it can become firm if a clot forms. The appearance ranges from small dots to large lesions involving skin and muscle.
Combined: The combined vascular anomalies present as an enlarged body part with a stain of the skin.
What are the most common complications of vascular malformations?
A facial CM can darken in color and the skin can thicken with aging. A tiny vascular growth called pyogenic granuloma, which may bleed easily, can appear at any age. CM can also be associated with overgrowth of the underlying soft tissues or bones. A rare condition called Sturge-Weber syndrome is composed of facial CM, bony overgrowth, and vascular anomalies of the lining over the brain that contains blood vessels.
The two major acute complications of LM are infection and bleeding into the tissues. Another long-term complication is overgrowth of involved tissues and bones. LM in the tongue, floor of the mouth, or near the windpipe can cause difficulty breathing, while LM in the gastrointestinal tract can cause protein loss. LM around the eye can cause it to protrude.
Intracranial AVM often occurs with headache or other neurological signs or with sudden bleeding into the brain. AVM outside the brain presents more slowly with color changes, then pulsations, later bleeding of the skin, and persistent pain. In time, if the blood flow through an AVM is excessive, the heart can become overloaded.
VM tends to grow at the same rate as the child. However, it can suddenly expand as the result of a clot within the VM. It may expand as a result of injury during puberty or pregnancy. A VM in the brain or gastrointestinal tract can suddenly bleed.
Combined vascular malformations are associated with minor to major overgrowth of both soft tissue and underlying bones. Fatty tissue overgrowth and elongation of bones can occur. The capillary-lymphatic vesicles often bleed, increasing the possibility of infection. Another complication is shunting of blood through the abnormal arteriovenous connections, causing pain, skin breakdown, and high output congestive heart failure.
How are vascular malformations treated?
The standard treatment for CM is use of a ‘flash lamp pulsed-dye’ laser. Some physicians prefer to treat the child under a general anesthetic; others use a local anesthetic cream. The overall response rate is 70-80% lightening of the stain. The outcome is usually better in the facial area than in the trunk or limbs.
LM is managed by either sclerotherapy (direct injection of an irritating solution) or surgical removal. Often it is difficult to totally remove LM. A drug called Sirolimus (rapamycin) can be effective treatment of LM.
Some intracranial AVM is treated by proton-beam radiation, while others can be treated by embolization (injection of material into the center of the anomaly by a catheter) and/or surgical excision (or removal). In other parts of the body, AVM is often treated either by embolization or sclerotherapy.
Only very tiny VM can be treated with a laser. The two main treatment strategies are sclerotherapy, often repeated, and surgical removal after sclerotherapy.
Children with complex combined vascular anomalies should be medically managed by appropriate members of an experienced interdisciplinary care team.
- Sam: The Boy Behind the Mask
Tom Hallman, Jr.
G.P. Putnam’s Sons, 2002
- Sam: The Boy Behind the Mask
- Vascular Anomalies Center
- Vascular Anomalies Center
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