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Capillary Lymphatic Venous Malformations (CLVM)

Last Updated 03/2022

What is a Capillary Lymphatic Venous Malformation?

Capillary lymphatic venous malformations (CLVMs) are rare blood vessel abnormalities that involve capillaries, veins, and lymphatic vessels. Patients with CLVMs have a capillary malformation, also called a port wine birthmark, that is next to or covers the abnormal veins and lymphatic vessels. CLVMs have a variety of looks and complications. Patients with these malformations may have a variety of soft tissue and bone overgrowth problems leading to different lengths or girths of the legs or arms, enlarged fingers or toes, and / or scoliosis (abnormal curvature of the spine/back).

Capillary lymphatic venous malformations form prior to birth. They are not caused by any exposures during pregnancy. Most CLVMs are identified at birth or in early childhood.

Capillary lymphatic venous malformations are found in two syndromes: Klippel-Trénaunay syndrome (KTS) and CLOVES syndrome. Individuals with KTS have soft tissue and / or bone enlargement of the extremity affected by the CLVM; not all patients with KTS have abnormal lymphatic vessels. The acronym CLOVES stands for: congenital lipomatous overgrowth, vascular malformations, epidermal nevi, scoliosis / skeletal and spinal abnormalities. Individuals with CLOVES syndrome may also have an arteriovenous malformation (AVM) in addition to a CLVM.

Most individuals with CLVM have been found to have a mutation in one copy of the PIK3CA gene in the overgrown tissue. This mutation is not inherited and is only found in the affected tissue(s).

What Does CLVM Look Like?

The capillary malformation (port-wine birthmark) is seen at birth. Oftentimes, not all components of the malformation can be seen with the naked eye and additional testing is needed.

Large dilated veins (similar to varicose veins) develop and get worse over time. Small bumps filled with clear fluid or lesions that look like blood blisters (called lymphatic blebs) may develop on the skin over the malformation. These lesions may become irritated and itch or bleed. Soft issue enlargement may be present at birth but usually increases and becomes more visible over time.

Bony problems are typically not present at birth but appear within the first few months or years of life.

In young adults, the capillary malformation may thicken and become more prominent or irritated.

How is CLVM diagnosed?

In most individuals, a medical history and physical examination are enough to make the diagnosis.

Large malformations may be diagnosed on prenatal ultrasound. The types of vessels involved and the size of the malformation is generally determined by magnetic resonance imaging (MRI) and / or ultrasonography (ultrasound). MRI is also helpful to evaluate soft tissue problems and to assess whether the malformation involves a joint.

Venography, a specialized procedure, may be used to assess venous structures and blood flow. Effects on bone growth are determined by plain X-rays.

What are the possible complications of CLVM?

Symptoms of CLVM vary. Pain and lymphedema (swelling of extremities) are common. Other complications include skin breakdown, bleeding (from lymphatic blebs) and infection.

Infection of the skin or soft tissues (cellulitis) is the most common type of infection in patients with CLVM. Cellulitis could lead to a more serious or even life-threatening infection. Immediate treatment with antibiotics is important to treat these infections.

Vein ectasias are common, and increase the risk of blood clots within the malformation (phleboliths) or in the superficial vein system. These blood clots may cause inflammation and pain (thrombophlebitis). Individuals with CLVM have an increased risk of developing blood clots in the deep veins (deep vein thrombosis, DVT) as well as in the blood vessels of the lungs (pulmonary emboli, PE), which can be life-threatening.

Rectal bleeding or blood in the urine may be seen if the lesion involves the intestine or bladder. Bleeding from lymphatic skin vesicles (lymphatic blebs) may also occur.

Skin ulcers, muscle cramping or joint pain when walking or abnormal sensations such as heaviness in the involved extremity may occur due to blood pooling or abnormal blood circulation.

Scoliosis, gait (walking) abnormalities and functional issues may be caused by bone and soft tissue problems related to CLVMs. When the malformation involves joints, chronic joint damage and pain may occur.

Treatment and Management

Should my child receive treatment?

All children with CLVM should complete a full evaluation by a CLVM specialist. Treatment decisions must be made on an individual basis.

How is CLVM treated?

Treatment of CLVMs depends on each person’s situation. Treatment is mostly supportive. Regular follow up is important.
  • Compression therapy. This involves wearing a tight-fitting garment which is typically custom-made to fit the affected body part (if possible). These garments help to control swelling and pain in the limb. They also help to protect the extremity from trauma. Compression pumps and lymphatic massage may also be helpful.
  • Orthopedic interventions. Shoe inserts are used to manage limb length discrepancies less than 1-2 inches. For greater discrepancies, surgery may be considered.
  • Sclerotherapy. This procedure involves injecting a chemical into an abnormal vein in order to scar down the abnormal vessel. The scar prevents blood or lymphatic fluid flow into the vein or lymphatic cyst. Sclerotherapy may also be used to decrease the size of the malformation or improve pain.
  • Drug therapy.
    • Low molecular weight heparin (enoxaparin, Lovenox): This medication is injected under the skin. This is a medication that can improve pain, phleboliths, and decrease the risk of bleeding and clotting around a procedure. LMWH is also used for the treatment or prevention of other blood clots, such as deep vein thromboses (DVTs) and pulmonary embolisms (PEs).
    • Topical sirolimus: This medication is applied directly to the affected skin. It is effective at treating superficial lymphatic blebs.
    • Oral sirolimus: This medication is taken by mouth. Oral sirolimus has shown to be effective at reducing signs/symptoms of disease. It can also improve the quality of life in children and adolescents with complex vascular anomalies, including CLVM.
    • Investigational agents are currently being tested in clinical research trials.
  • Surgical options. There are a variety of surgical options, depending on each person’s situation. These include vein ablation, vein resection, and in some cases, debulking or amputation. Vein ablation is a procedure that closes down a section of veins. This clamp prevents blood flow through the damaged section of veins and promotes blood flow through veins that are not damaged.
  • Laser therapy. Pulsed-dye laser may be helpful in lightening the color of the capillary malformation component (port-wine birthmark) of the CLVM. Laser is a good option for capillary malformation on the face, but often is not as effective on the trunk, legs and arms. Multiple treatments are required to achieve a desirable result. Laser therapy with a different laser (KTP) may be used to treat bleeding or leaking lymphatic blebs.

Are there any risks associated with treatment?

The treatment approaches have benefits that improve the functioning and emotional wellbeing of the child., Each of these management approaches has drawbacks and limitations:

  • Sclerotherapy. In rare events, blistering, scarring, infection, numbness or localized tissue loss may occur. In some cases, the malformation may shrink but then reappear or enlarge over time. In other cases, the malformation may not respond to sclerotherapy treatment.
  • Drug therapy
    • Low molecular weight heparin (enoxaparin, Lovenox): The most common side effects are bruising and/or irritation or pain at the injection site. There is an increased risk of bleeding.
    • Topical sirolimus: There is small risk of systemic absorption if used as prescribed. Topical sirolimus may cause skin irritation.
    • Oral sirolimus: This medication has potential side effects. Prior to starting, your provider will review side effects of this medication with you.
  • Surgical options. Some degree of scarring will occur with surgery. Surgical interventions may also cause damage to structures involving or near the malformation.
  • Vein ablation. Bruising, swelling, and pain at the site of ablation may occur initially after the procedure. Rarely, complications such blood clots or nerve injury could occur.
  • Laser therapy. This procedure may result in some tissue scarring and/or changes in skin pigmentation.
Reviewed By Adrienne Hammill, MD, PhD, and Kiersten Ricci, MD

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