KTS is caused by a genetic variation that occurs during fetal development. Why this occurs is unknown.

Symptoms of KTS include:

• Many port wine stains or other blood vessel problems, including dark spots on the skin
• Varicose veins (may be seen in early infancy, but are more likely to be seen later in childhood or adolescence)
• Unstable gait due to limb-length difference (involved limb is longer)
• Bone, vein, or nerve pain

Other possible symptoms:

• Bleeding from the rectum
• Blood in the urine

People with this condition may have excessive growth of bones and soft tissue. This occurs most commonly in the legs, but it also may affect the arms, face, head, or internal organs.

Various imaging techniques can be used to find out any change in body structures due to this condition. These also help in deciding the plan of treatment. These may include:

• MRA
• Endoscopic thermal ablation therapy
• X-rays
• CT scans or CT venography
• MRI
• Color duplex ultrasonography

Rarely would an ultrasound during pregnancy help detect the condition.

More information and support for people with KTS and their families can be found at:

• The Klippel-Trenaunay Syndrome Support Group -- k-t.org
• Vascular Birthmarks Foundation -- birthmark.org

Most people with KTS do well, although the condition may affect their appearance.

Klippel-Trenaunay-Weber syndrome; KTS; Angio-osteohypertrophy; Hemangiectasia hypertrophicans; Nevus verucosus hypertrophicans; Capillary-lymphatico-venous malformation (CLVM)

Greene AK, Mulliken JB. Vascular anomalies. In: Losee JE, Hopper RA, eds. Plastic Surgery: Volume 3: Craniofacial, Head and Neck Surgery and Pediatric Plastic Surgery. 5th ed. Philadelphia, PA: Elsevier; 2024:chap 31.

K-T Support Group website. Clinical practice guidelines for Klippel-Trenaunay syndrome (KTS). k-t.org/assets/images/content/BCH-Klippel-Trenaunay-Syndrome-Management-Guidelines-1-6-2016.pdf. Updated January 6, 2016. Accessed April 18, 2024.

Longman RE. Klippel-Trenaunay-Weber syndrome. In: Copel JA, D'Alton ME, Feltovich H, et al, eds. Obstetric Imaging: Fetal Diagnosis and Care. 2nd ed. Philadelphia, PA: Elsevier; 2018:chap 131.

McCormick AA, Grundwaldt LJ. Vascular anomalies. In: Zitelli BJ, McIntire SC, Nowalk AJ, Garrison J, eds. Zitelli and Davis' Atlas of Pediatric Physical Diagnosis. 8th ed. Philadelphia, PA: Elsevier; 2023:chap 10.

Updated by: Anna C. Edens Hurst, MD, MS, Associate Professor in Medical Genetics, The University of Alabama at Birmingham, Birmingham, AL. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.