Vascular Malformations Program

Question: I recently met someone whose 5 year old son has Klippel-Ternaunay syndrome. His leg was very swollen and red. What is it, and what causes it?

Answer: Thank you for contacting this “Ask the Expert” forum for pediatrics. We spoke to Dr. Patricia Burrows, director of the vascular malformations program at Memorial Hermann Hospital-Texas Medical Center. She said that Klippel-Trenaunay syndrome (KTS) is a type of slow flow vascular (blood vessel) malformation with overgrowth of the affected limb. A vascular malformation consists of blood and lymphatic vessels that form abnormally. It most frequently affects the leg and adjacent hip and it varies in severity from a birthmark with varicose veins to a severely deformed and enlarged limb and pelvis. To be considered KTS, the patient must have a capillary malformation [port wine stain or birthmark], varicosities, which represent enlarged anomalous veins and a lymphatic component. The lymphatic component can range from some small vesicles or bubbles on the skin to extensive cysts in the leg and/or pelvis. The typical symptoms include painful swelling and heaviness of the limb, making it difficult to walk. The cause of this syndrome is not known, but most vascular malformations are believed to be the result of mutations that occur after conception. It usually is not hereditary. We encourage you to contact the Vascular Malformations Program at 713-704-6762 for an appointment if you or someone you know would like an expert examination and the most up to date treatments available. There is also a nationally-based support group for KTS, with information at the website.