Klippel-Trénaunay syndrome (KTS) is a genetic condition in which capillaries, veins and lymph vessels do not form properly (malformation). These malformations are present from birth (congenital) and can worsen over time. KTS is characterised by overgrowth of an affected limb involving bones and/or soft tissue, and specific vascular malformations resulting in skin discolouration sometimes called a ‘port wine stain’ as well as twisted and swollen veins (varicosities) that often bulge out from the skin.¹ KTS usually affects one leg only, but in rare cases can involve arms, the head, trunk, or multiple areas. Overgrowth of the affected limb often stops when other limbs stop growing.

Klippel-Trenaunay syndrome was historically used to refer to a wider group of vascular anomalies with overgrowth; however, this has been recognised to be inaccurate and KTS is now restricted to abnormalities in the capillaries, veins and lymph vessels with overgrowth.²

Synonyms: KT syndrome, angio-osteohypertrophy syndrome, CLMV (Capillary, Lymphatic, Venous Malformations).^3,4

Please note that Klippel-Trénaunay syndrome and Parkes Weber syndrome were previously both referred to as Klippel-Trénaunay-Weber syndrome; however, Klippel-Trénaunay syndrome and Parkes Weber syndrome are now classified as two separate conditions.²

Universal rare disease classifications provide a common language for recording, reporting and monitoring diseases. Please visit the Rare Disease Classifications page for more information about these internationally recognised classifications.

ORPHA:90308 Klippel-Trénaunay syndrome

ICD-11:D26.60 Angio-osteohypertrophic syndrome

The symptoms of KTS vary between individuals but generally include:^1,5,6

• unusual growth rate and swelling of the affected limb/s (bone and soft tissue hypertrophy, lymphoedema). Usually, the affected limb is longer and/or wider than the unaffected limb;however, in rare cases it can be smaller. The size difference between limbs varies greatly between individuals. Swelling can increase and become painful when the limb is in use
• birth marks (cutaneous haemangioma) or other areas of discoloured skin which may be painful and begin to ooze clear fluid (lymph) and/or develop black spots with age.
• bumpy or twisted veins causing a raised and discoloured area on the skin (varicose veins). These may become swollen, sore, and more visible with age
• the foot opposite the affected limb often becomes swollen and accumulates fat

Common complications include chronic pain, blood clotting disorders (coagulopathies), blood clots in the arteries or veins (thrombosis), blood clots that affect the lungs (pulmonary embolisms), and internal bleeding.¹

Please speak to your medical team to learn more about the symptoms and complications of KTS.

Rare diseases are often serious and progressive, exhibiting a high degree of symptom complexity, leading to significant disability. Majority of the estimated two million Australians living with a rare disease meet the Australian Government’s definition for disability (in accordance to the Australian Public Service Commission and Australian Bureau of Statistics), and many experience severe and permanent disability impacts. If you or someone you care for is experiencing disability-related impacts from a rare condition, please speak with a health or disability professional for advice. Information about relevant disability support can be found at the RARE Portal’s Disability Support Information page.

KTS is one of many conditions associated with disease-causing genetic variants (changes) in the PIK3CA gene.^1,6,7 These conditions are collectively known as the PIK3CA-related overgrowth spectrum (PROS) and have many overlapping features.

In KTS, the genetic variants in PIK3CA occurs randomly (de novo) before birth but is not in all cells of the body (genetic mosaicism).⁷ As the genetic change is somatic (not in germ cells such as sperm or eggs cells), it is not passed on to the next generation (not inherited). More information on genetic mosaicism can be found at Centre for Genetics Education: Mosaicism.

If you would like to learn more about the inheritance and impact of this condition, please ask your doctor for a referral to a genetic counsellor. Genetic counsellors are qualified allied health professionals who can provide information and support regarding genetic conditions and testing. More information on genetic counselling can be found at:

• Information on Genetic Services
• National and State Services pages underneath the ‘Genetic Counselling’ sections listed

KTS may be diagnosed based on a physical examination of the signs and symptoms. Imaging scans, such as computed axial tomography (or CT scans) and magnetic resonance imaging (MRI), and colour doppler studies (ultrasound), may be performed to identify and assess the extent of malformations and to guide treatment.¹

Genetic testing for PIK3CA somatic mosaicism (in which not all the cells in the body have a PIK3CA genetic change) may be performed; however, not all individuals may have a detectable PIK3CA mutation.⁶

A differential diagnosis can rule out other condition that have similar symptoms, such as Parkes-Weber syndrome, CLOVES syndrome, other PIK3CA-related overgrowth spectrum (PROS) syndromes, PTEN-related overgrowth disorders, Proteus syndrome and DCMO syndrome.^5,6

Please speak to your medical team to learn more about the available diagnostic pathways for KTS.

There is currently no curative treatment for KTS. Treatment is targeted at managing symptoms (symptomatic management) and involves a multidisciplinary care team. Management strategies may include compression therapy to minimise swelling and reduce overgrowth.⁵ Compression stockings, bandages or custom-made compression garments may be worn for life, or only through significant periods of growth, depending on an individual’s requirements. Specialised (orthopaedic) shoes or shoe inserts may be used to manage uneven leg length, and physiotherapy or occupational therapy may be used to improve mobility.

Sclerotherapy, radiofrequency ablation or similar interventions may be able to remove some swollen veins, which can reduce the risk of some complications and may also improve the cosmetic appearance.⁸ Laser treatment may be used to lighten birthmarks and port wine stains.

Surgical intervention for KTS is rare.⁵ It is important to note that there may be special considerations for individuals with KTS requiring general anaesthetic.⁹

The management of KTS may also involve monitoring for signs of blood clots and in some cases, blood thinning medication may be given to prevent complications from blood clots.¹

Please speak to your medical team to learn more about the possible treatment or management options for your condition. Treatment will depend on an individual’s specific condition and symptoms. It is also important to stay connected to your medical team so that you can be made aware of any upcoming clinical trial opportunities.

Clinical care for rare diseases often involves a multidisciplinary team of medical, care and support professionals. Please note that the information provided here is as a guide and that RVA does not necessarily monitor or endorse specific clinics or health experts.

Healthcare professionals involved in the treatment of KTS may include general practitioners (GP), paediatricians, geneticists, dermatologists, physiotherapists, occupational therapists, lymphoedema therapists, interventional radiologists, and orthopaedic specialists. The need for different healthcare professionals may change over a person’s lifetime and extend beyond those listed here.

We are not aware of any clinical care guidelines for KTS in Australia. If you know of any relevant care guidelines, please let us know via the Contribute page.

The following guidance is available from international experts outside Australia; however, there may be information that is not relevant or applicable to the Australian context, and may not be up to date:

• Klippel-Trenaunay Syndrome Management Guidelines is available on the K-T Support Group (United States); it is ‘developed by a team of vascular anomalists at the Boston Children’s Hospital as a booklet of management guidelines to assist physicians and patients’; please note this was published in 2016.
• OrphanAnesthesia has Anaesthesia recommendations for patients suffering From Klippel-Trénaunay syndrome, please note that this was last modified in 2017 and may not be up to date.

Individuals living with rare diseases may have complex medical issues and disabilities, which are not always visible. It is often useful to refer to their medical history as well as personal information such as a medical card, doctor’s letter, or if available, a rare disease passport, for relevant information.

OrphanAnesthesia has Anaesthesia recommendations for patients suffering From Klippel-Trénaunay syndrome, please note that this was last modified in 2017 and may not be up to date.

There are specific considerations around participating in rare disease research, including clinical trials. It is important to be mindful of issues such as data privacy, research ethics, consent and differences in research regulations between Australia and other countries.

If you are interested in finding clinical trials for your condition, please visit the following websites; however, there may not be any clinical trials available:

• Australian Clinical Trials
• ClinicalTrials.gov

It is best to discuss your interest in any clinical trials with your medical team to determine suitability and eligibility.

Please note that RVA does not necessarily monitor or endorse each group/organisation’s operational governance and activities.

There are currently no known organisations for KTS in Australia. If you are aware of any KTS organisations in Australia, please let us know via the Contribute page.

International Organisations:

KT-Support Group (United States of America)
Website: https://k-t.org/

The Vascular Birthmarks Foundation (Global)
Website: https://birthmark.org/birthmark/klippel-trenaunay-syndrome/

Please note that RVA does not monitor or endorse each group/organisation’s operational governance and activities. When engaging with a group, please consider the information on the RARE Portal’s Finding Helpful Peer and Community Supports page.

KTS varies between individuals, and each person’s experience is unique.

Personal Story shared with Rare Voices Australia: Bridie’s Story.

If you would like to share your personal story with RVA, please visit the Rare Voices Australia: Share Your Story page. RVA will consider your story for publishing on our website and inclusion on the RARE Portal.

For information on available government and social services that provide support for individuals with a rare disease, please visit the National and State Services pages.

People living with a rare disease, including families and carers, often face unique challenges such as diagnostic delays, misdiagnoses, limited treatment options, and limited access to rare disease specialists and support. These challenges may impact people’s emotional wellbeing and quality of life. Many people find it helpful to seek mental health and wellbeing support to cope with ongoing stress and uncertainty. Connecting with people who have shared experiences through a support group may also be helpful. Information about relevant mental health and wellbeing support can be found at:

• Mental Health and Wellbeing Support for Australians Living with a Rare Disease
• The National and State Services pages underneath the ‘Mental Health’ sections listed

Further information on KTS can be found at:

• Children’s Health Queensland: Klippel-trenaunay syndrome
• National Organization for Rare Disorders (NORD): Klippel-Trenaunay syndrome

• Children’s Health Queensland: Klippel-Trenaunay syndrome
• GeneReviews^®: PIK3CA-Related Overgrowth Spectrum
• Online Mendelian Inheritance in Man, OMIM^®: #149000, Klippel-Trenaunay Syndrome
• Orphanet: Klippel-Trénaunay syndrome
• International Society for the Study of Vascular Anomalies (ISSVA): ISSVA Classification of Vascular Anomalies was approved at the 20th ISSVA Workshop in Melbourne in April 2014 and last reviewed in May 2018.

This page has been developed by Rare Voices Australia (RVA)’s RARE Portal team.

If you are aware of any additional information that may benefit stakeholders with an interest in this page, or if you notice any broken links or inaccurate information, please let us know via the Contribute page.