Klippel-Trenaunay-Weber syndrome (KTWS) is a rare congenital vascular condition in which blood vessels and/or lymphatic vessels do not develop properly, causing a limb to develop port wine stains (red-purple birthmarks involving blood vessels), varicose veins, and/or excessive bone and soft tissue regeneration. The limb could be bigger, lengthier, or warmer than usual.
The presence of a combination of these symptoms (typically on around ¼ of the body, though certain cases may display more or less damaged tissue) indicates the presence of a birth defect: