Klippel-Trenaunay Syndrome (KTS)


Klippel-Trenaunay Syndrome (KTS) is a rare congenital disorder characterized by abnormal development of certain blood vessels, soft tissues (including skin and muscles), bones, and occasionally the lymphatic system. It is usually identified at birth and presents with distinctive features such as a port-wine stain birthmark, which can range from pink to reddish-purple in color, abnormal formations in veins or the lymphatic system, and the overgrowth of tissues and bones. Although these symptoms primarily affect one leg, they can also manifest in an arm or other parts of the body. While there is no cure for KTS, treatments are available to help manage its symptoms. Health professionals typically detect and diagnose KTS shortly after birth, and prompt treatment can mitigate the risk of further health issues associated with the condition.


Klippel-Trenaunay Syndrome (KTS) is characterized by a distinctive set of symptoms and complications, primarily affecting the skin, veins, soft tissues, bones, and the lymphatic system.

The primary features include:

  • Capillary malformation (CM): A hallmark of KTS is the appearance of port-wine stain birthmarks, resulting from swollen capillaries beneath the skin. These birthmarks can range in color from light pink to deep wine-red and may change shade over time. With age, the birthmarks can develop small blisters, which might burst or bleed. Typically, these birthmarks are among the first indications of KTS.
  • Lymphatic malformation (LM): KTS may also involve abnormalities in the lymphatic system, with some individuals having extra or irregularly formed lymph vessels. These vessels may not function properly, leading to leakage of lymph fluid or swelling of the feet. Issues with lymph vessels can extend to the pelvis, bladder, or lower intestines.
  • Vein malformation (VM): Almost every individual with KTS experiences venous malformations, affecting both superficial and deep veins. Superficial malformations can lead to varicose veins, primarily on the calves and thighs, which are twisted, swollen, and can cause discomfort or itchiness. Malformations in deeper veins may heighten the risk of deep vein thrombosis (DVT), potentially leading to swelling, pain in the lower limbs, and an increased risk of gastrointestinal (GI) tract bleeding due to venous malformations.
  • Soft tissue and bone overgrowth: A characteristic overgrowth of limbs can begin in infancy, typically affecting only one limb—often the leg. This overgrowth can cause a discrepancy in limb length, leading to pain, a sensation of heaviness, and a reduced range of motion.

Complications associated with KTS include:

  • Blood clots
  • Cellulitis (bacterial infections below the skin)
  • Lymphedema (fluid buildup and swelling)
  • Internal bleeding (including in the colon, bladder, or female reproductive system)
  • Pulmonary embolism (a critical condition when blood clots move to the lungs)

Additional Congenital Differences: Though less common, some individuals with KTS might have congenital differences in their hands or toes, such as extra fingers or toes (polydactyly) or fused fingers or toes (syndactyly).


While Klippel-Trenaunay syndrome (KTS) can be hereditary, not all cases are inherited. The condition is typically caused by genetic alterations or mutations, with the PIK3CA gene being most commonly implicated. This gene plays a crucial role in tissue formation and cell proliferation within the body. Mutations in the PIK3CA gene lead to tissue overgrowth. These genetic alterations occur randomly during early development, specifically before birth, during cell division.

Risk factors

It is unlikely that parents of one child with KTS would have another child with the medical conditions, even if one of the parents has KTS. Family history does not appear to be a risk factor.