Reviewed by Brian R. Robinson, MD
Klippel-Trenaunay-Weber syndrome (KTWS), commonly known as a “port wine stain” is a rare congenital defect. Those affected have hypertrophied limbs (abnormal overgrowth of bone and soft tissue), birthmarks that form in large, dark red, blotchy patterns, and varicose veins or other venous insufficiencies. The cause of KTWS is unknown.
KTWS is a congenital mesodermal defect consisting of a triad of three main abnormalities: hemangiomas, hypertrophy of the limbs (enlargement of the bone and soft tissue, sometimes leading to one limb growing longer than the other) and venous anomalies.
Hypertrophy of the limbs may be barely noticeable, or it may lead to difficulty walking, pain, and orthopedic problems in more severe cases.
Venous anomalies may also include lack of valves in the deep veins or even total lack of veins (agenesis), partial lack of deep veins, congenital varicose veins that represent the only venous drainage of the limb, venous swelling, and potentially ulceration of the skin.