Klippel-Trenaunay (klih-PEL tray-no-NAY) syndrome is a rare disorder found at birth (congenital) involving abnormal development of blood vessels, soft tissues, bones and the lymphatic system. Rarely, fusion of fingers or toes, or having extra fingers or toes, also occurs at birth.

People who have Klippel-Trenaunay syndrome may have the following features, which can range from mild to more extensive:

  • Port-wine stain. This pink to reddish-purple birthmark is caused by swelling of tiny blood vessels (capillaries) under the skin. The birthmark usually covers part of one leg, and sometimes one arm, and may get darker or lighter with age. Some areas may be prone to bleeding and infections.
  • Vein malformations. These include swollen, twisted veins (varicose veins) usually on the surface of the legs, which can cause major pain and skin ulcers due to poor circulation. Deeper abnormal veins in the arms, legs, abdomen and pelvis can increase the risk of blood clots (deep vein thrombosis) and cause a life-threatening condition called pulmonary embolism if they dislodge and travel to the lungs. Spongy tissue filled with small veins in or under the skin can cause bleeding, infection or inflammation.
  • Overgrowth of bones and soft tissue. This begins in infancy and is usually limited to one leg, but it can occur in an arm or, rarely, in the trunk. This overgrowth of bone and tissue creates a larger and longer extremity. The overgrowth can cause pain, a feeling of heaviness and problems with movement.
  • Lymphatic system abnormalities. The lymphatic system is part of your immune system, which protects you against infection and disease. An abnormality can cause fluid buildup and swelling in the tissues of your arms or legs (lymphedema), the development of small masses (lymphatic cysts) in the spleen, or infection of the layer under the skin (cellulitis).

The cause of Klippel-Trenaunay syndrome is unknown, but may involve genetic changes that are not inherited (mutations). But more research is needed to determine the causes.

  • Experience. Doctors at Mayo Clinic are among the most experienced in the diagnosis and treatment of Klippel-Trenaunay syndrome.
  • Teamwork. Doctors who specialize in vascular medicine, vascular and endovascular surgery, skin disease (dermatology), orthopedic surgery, pediatrics, and other areas as needed, offer many treatment options. This coordinated approach is important because Klippel-Trenaunay syndrome may involve several parts of the body.

Diagnosis of Klippel-Trenaunay syndrome begins with a physical exam. Referral to a vascular specialist is helpful for evaluation and treatment recommendations. During the evaluation your doctor:

  • Asks you questions about your family and medical history
  • Examines you for swelling, varicose veins and port-wine stains
  • Visually evaluates growth of your bones and soft tissues

Several diagnostic tests can help your doctor evaluate and determine the type and severity of your condition:

  • Duplex scanning. This test uses high-frequency sound waves to create detailed images of your blood vessels.
  • Scanogram. Also called scanner photography, this X-ray technique helps your doctor see images of your bones and measure their lengths.
  • Magnetic resonance angiography. This procedure helps your doctor differentiate between bone, fat, muscle and blood vessels.
  • CT scan. A CT scan creates 3-D images of your body that help your doctor look for blood clots in veins.
  • Contrast venography. This procedure involves injecting a dye into your veins and taking X-rays that can reveal abnormal veins, blockages or blood clots.

Although there is no cure for Klippel-Trenaunay syndrome, Mayo Clinic experts can help you manage your symptoms and prevent complications. You and your doctor can work together to determine which of the following treatments are most appropriate for you:

  • Compression therapy. Bandages or elastic garments are wrapped around affected limbs to help prevent swelling, varicose veins and skin ulcers. Intermittent pneumatic compression devices — leg or arm sleeves that automatically inflate and deflate at set intervals — may be used.
  • Lifestyle management. Orthopedic shoes may improve your health and physical function.
  • Physical therapy. Massage, compression and encouraging use of the limb as appropriate may help relieve swelling in your arms or legs (lymphedema) and swelling of the blood vessels.
  • Epiphysiodesis (ep-ih-fiz-e-OD-uh-sis). This is an orthopedic procedure that effectively can stop overgrowth of the lower limb.
  • Embolization. This procedure, performed through small catheters placed into the veins or arteries, blocks blood flow to certain blood vessels.
  • Laser therapy. This procedure may lighten or eliminate port-wine stains on your skin.
  • Laser or radiofrequency ablation of veins. This minimally invasive procedure is used to close off abnormal veins.
  • Sclerotherapy. Your doctor injects a solution into your vein, which creates scar tissue that helps close the vein.
  • Placement of a vena cava filter. This procedure prevents blood clots from traveling to your lungs.
  • Surgery. In some cases, you may benefit from removal or reconstruction of your affected veins and correction of the overgrowth of bone.

In addition, you may need treatment for complications such as bleeding, infection, blood clots or skin ulcers.

Early research indicates that a drug called sirolimus may help prevent the growth of vascular malformations, but it may have significant side effects and more studies are needed.

Mayo Clinic works with hundreds of insurance companies and is an in-network provider for millions of people. In most cases, Mayo Clinic doesn't require a physician referral. Some insurers require referrals or may have additional requirements for certain medical care. All appointments are prioritized on the basis of medical need.

At Mayo Clinic's campus in Arizona, the Vascular Center includes specialists in vascular medicine, vascular surgery (cardiac surgery), skin diseases (dermatology), orthopedic surgery, and other areas as needed, who work together to diagnose and treat Klippel-Trenaunay syndrome.

For appointments or more information, call the Central Appointment Office at 800-446-2279 (toll-free) 8 a.m. to 5 p.m. Mountain Standard Time, Monday through Friday or complete an online appointment request form.

At Mayo Clinic's campus in Florida, the Vascular Center includes specialists in vascular medicine, vascular surgery (cardiac surgery), skin diseases (dermatology), orthopedic surgery, and other areas as needed, who work together to diagnose and treat Klippel-Trenaunay syndrome.

For appointments or more information, call the Central Appointment Office at 904-953-0853 8 a.m. to 5 p.m. Eastern time, Monday through Friday or complete an online appointment request form.

At Mayo Clinic's campus in Minnesota, the Gonda Vascular Center includes specialists in vascular medicine, vascular surgery, skin diseases (dermatology), orthopedic surgery, pediatrics, and other areas as needed, who work together to diagnose and treat Klippel-Trenaunay syndrome.

For appointments or more information, call the Central Appointment Office at 507-538-3270 7 a.m. to 6 p.m. Central time, Monday through Friday or complete an online appointment request form.

See information on patient services at the three Mayo Clinic locations, including transportation options and lodging.

See a list of publications by Mayo Clinic authors on Klippel-Trenaunay syndrome on PubMed, a service of the National Library of Medicine.

Sept. 17, 2015