Klippel-Trénaunay syndrome (KTS) refers to a condition that impacts the development of blood vessels, soft tissues, and bones. It often presents with characteristic features, such as a red or purple birthmark, an overgrowth of soft tissues and bones, and vein problems.

KTS describes a rare condition that affects the development of tissues that is present from birth. The name of the condition derives from French physicians Maurice Klippel and Paul Trénaunay.

In this article, we will discuss Klippel-Trenaunay syndrome, including symptoms, causes, and treatment options.

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Klippel-Trénaunay syndrome (KTS) refers to a rare condition that involves a collection of symptoms that often appear together. Typically, the syndrome involves three characteristic features:

  • a red-purple birthmark called a port-wine stain
  • overgrowth of soft tissues and bones, typically present in one limb
  • vein-related conditions such as varicose veins

The condition is congenital, meaning it is present from birth. Many people have a port-wine stain from birth and later develop other symptoms such as extra limb growth and vein problems.

Confusingly, some people may use the term Klippel Trénaunay Weber syndrome. However, the Weber part of the name instead refers to a separate, distinct condition known as Parkes-Weber syndrome, which also impacts blood vessels.

Therefore, some health experts may instead refer to KTS as capillary-lymphatic-venous malformation (CLVM) because of the changes that occur in the capillaries, lymphatics, and veins.

Currently, researchers are still unsure of the exact cause of KTS. However, research suggests that several genes and pathways likely play a role. Notably, evidence associates alterations in the phosphatidylinositol-4-5-bisphosphate 3 kinase catalytic subunit, or PIK3CA gene, with the development of KTS.

This gene is responsible for making a protein that forms part of an enzyme known as PI3K. This enzyme is very important for many cell activities, including cell growth and division, production of new proteins, transporting materials within cells, and cell survival.

A somatic alteration, or alteration in DNA after fertilization, causes a change in the PIK3CA gene. This change alters the protein that PIK3CA produces, which makes PI3K more active than usual. This higher activity results in excessive growth of bones, soft tissues, and blood vessels, which leads to the symptoms of KTS.

As such, healthcare professionals may describe KTS as a condition on the PIK3CA-related overgrowth spectrum (PROS). This term refers to a group of genetic conditions that involve the overgrowth of various body parts due to changes in the PIK3CA gene.

Evidence notes that KTS can affect children of all ethnic groups and occurs in males and females in equal numbers. Research estimates that the condition impacts roughly 1 in 100,000 people worldwide.

KTS is a complex condition that may involve an individual presenting with a variety of symptoms. However, KTS has three characteristic features that include:

  • Port-wine stain: This is a birthmark caused by small blood vessels (capillaries) swelling near the skin surface. Port-wine stains are normally flat and can range from pale pink to purple in color. A port-wine stain is present in 90–100% of KTS cases and typically covers part of one limb.
  • Bone and soft tissue overgrowth: A person with KTS may experience unusual growth of tissue. This typically only occurs in one limb, such as a leg. The growth may cause a person to experience pain and a feeling of heaviness. It may also impact on the range of movement of the affected limb. Limb hypertrophy occurs in 67% of KTS cases, 88% of which involve a lower limb and 71.5% involve a single limb.
  • Vein problems: The veins are the blood vessels that return blood to the heart to refill it with oxygen. In KTS, the veins may swell and twist close to the skin’s surface and cause pain. This is known as varicose veins and occurs in 72% of KTS cases.

Other possible symptoms of KTS may include:

  • lymphatic problems, such as swelling or cysts
  • cellulitis, or skin infections
  • blood clots
  • anemia
  • internal bleeding

A doctor will typically diagnose KTS based on physical examinations and may also order tests to confirm the diagnosis. Initially, a doctor may suspect KTS in children with a port-wine stain covering an arm or leg.

However, they may not confirm the diagnosis until varicose veins and limb hypertrophy are more obvious. Usually, a doctor will diagnose the condition if a person presents with two of the three classic signs.

A doctor may order additional imaging tests to determine the severity and extent of problems with capillaries, lymphatics, and veins. Imaging tests a doctor may request include:

  • a color doppler ultrasound
  • a magnetic resonance imaging (MRI) scan
  • a magnetic resonance venography (MRV) scan

Currently, there is no cure for KTS, and the goal of treatment is to reduce symptoms. Treatment may require a multi-disciplinary team approach:

  • Skincare: It is vital to prevent infections of the skin and bleeding from scratching. A person may also receive antibiotics and pain medication to help manage infections.
  • Orthotics: A doctor may monitor any discrepancies in limb length and suggest orthotics or surgical corrections as necessary
  • Compression stockings: These stockings apply pressure to the legs to help maintain blood flow and prevent swelling.
  • Sclerotherapy: This treatment for varicose veins involves injecting a solution into blood or lymph vessels that causes them to shrink.
  • Laser treatment: Options such as a pulse dye laser (PDL) may help treat the appearance of port-wine stains. A 2019 study on infants with port-wine stains notes that 41.1% of people had a 76–99% improvement in port-wine stain appearance, while 25.9% had 100% clearance of their port-wine stains.
  • Rapamycin: Also known as sirolimus, this drug may help prevent symptoms of KTS by stopping a protein known as mTOR1 from working. However, due to the drug’s adverse effects, a doctor will need to monitor an individual taking rapamycin.

KTS is often a progressive disorder and the prognosis of an individual will depend on the severity of the symptoms.

While some symptoms of the condition may be severe, a person can typically manage them with regular doctor appointments and following their treatment plan. Evidence notes that many individuals live well while managing the symptoms of the disorder.

Klippel-Trenaunay syndrome (KTS) is a rare condition that causes problems with tissues in the body, including blood vessels, lymph vessels, bone tissue, and soft tissue. The three classic signs of KTS include a port-wine stain, bone and tissue overgrowth, and vein problems.

Researchers believe a genetic alteration in the PIK3CA gene may relate to the development of KTS. A doctor will diagnose a person by completing a physical examination and conducting imaging tests.

Treatment options will vary depending on the severity of the condition and typically involves managing symptoms through treatment options such as laser therapy, sclerotherapy, skincare treatment, surgery, or drug therapy.