Klippel-Trenaunay Syndrome (KT) is a rare birth defect that gives one limb too many veins, too few lymph channels, and extra bone growth. Signs usually show up in infancy and stick around for life. Port-wine stain is the headline. A flat, pink-to-purple birthmark wraps around the outer thigh or buttock on the affected leg. Vein overgrowth follows. Ropey varicose veins pop out early—sometimes before the child can walk—and get thicker with age. Leg swelling is common. The limb feels heavy and puffy by day, and socks leave deep grooves at the ankle. Length difference shows up next. One leg grows... Learn more