Klippel–Trénaunay Syndrome – Expert Diagnosis & Multidisciplinary Skin Care in London

What is Klippel–Trénaunay syndrome (KTS)?

Klippel–Trénaunay syndrome is a rare, congenital disorder of the blood and lymphatic vessels and surrounding tissues. It is defined by three hallmark features: (1) a capillary malformation known as a port‑wine stain; (2) venous malformations or atypical varicose veins that may include persistent embryonic veins and deep venous anomalies; and (3) limb overgrowth, involving soft tissue and/or bone, resulting in increased limb length or circumference. KTS most often affects one lower limb, though upper limbs and, less commonly, both limbs can be involved.

Historically, the term “Klippel–Trénaunay–Weber syndrome” was used, but modern usage distinguishes KTS (a low‑flow condition) from Parkes Weber syndrome, which is associated with high‑flow arteriovenous fistulas. Clarifying this distinction matters because management strategies differ and high‑flow shunts require different interventional approaches.

Causes and how KTS develops

Current evidence links KTS to mosaic mutations in the PIK3CA gene, which regulates the PI3K–AKT–mTOR pathway controlling cell growth and angiogenesis. When a mutation occurs early in embryonic development, a patchwork (mosaic) of affected tissues emerges, leading to asymmetric overgrowth and malformed vessels. KTS is therefore classified within the PIK3CA‑Related Overgrowth Spectrum (PROS). These mutations are somatic (not inherited in the traditional sense) and arise sporadically; most families have no prior history of KTS.

Disordered vascular development can involve capillaries (flat red birthmarks), superficial and deep veins (varicosities, venous lakes, marginal or persistent embryonic veins), and lymphatic channels (causing swelling or vesicles). Bone growth plates and soft tissues may also be affected, driving limb length discrepancy and enlargement.

Symptoms and patterns in Klippel–Trénaunay syndrome

Presentation varies widely. Many individuals are identified in infancy due to a port‑wine stain and enlargement of one limb. Others present later with pain, heaviness, swelling (oedema), or recurrent skin infections. Typical features include:

• Capillary malformation: A flat pink‑red birthmark, often geographic in outline. Colour can darken with age.
• Venous malformations and varicosities: Visible, sometimes tortuous veins over the affected limb. Deep venous anomalies (hypoplasia, aplasia, or aneurysms) can impair venous return and increase clot risk.
• Limb overgrowth and length discrepancy: Increased girth and/or length, often of a leg. This may alter gait, shoe fitting, posture, and spinal alignment over time.
• Lymphatic involvement: Localised swelling, lymphatic vesicles that may ooze, and predisposition to cellulitis.
• Skin changes: Thickening, hyperkeratosis around the ankle, eczema from chronic oedema, and a tendency to ulcerate at pressure points.
• Functional impact: Reduced endurance, difficulty with long periods of standing, footwear challenges, and psychosocial distress due to appearance differences.

Potential complications

Without appropriate support, KTS can lead to significant morbidity:

• Thromboembolism: Superficial thrombophlebitis and deep vein thrombosis (DVT) can occur, especially when deep venous anomalies are present. In rare cases clots can travel to the lungs causing pulmonary embolism (PE).
• Chronic venous insufficiency: Persistent pooling of blood contributes to oedema, skin inflammation, darkening (haemosiderin), and venous leg ulcers.
• Recurrent cellulitis and infection: Related to lymphatic dysfunction, skin breaks, and ulcers.
• Bleeding: Fragile venous malformations or visceral involvement (e.g., bowel, bladder) can cause bleeding. Rarely, anaemia may develop.
• Orthopaedic issues: Limb length discrepancy may cause knee, hip, or back pain, altered gait, and uneven wear of joints if not addressed.
• Psychological impact: Chronic symptoms and visible differences can affect confidence, schooling, employment, and relationships.

How Klippel–Trénaunay syndrome is diagnosed

Diagnosis is primarily clinical, based on the classic triad and distribution. Supportive investigations define the extent and guide treatment:

• Doppler ultrasound: Assess superficial and deep venous anatomy, flow patterns, and thrombus.
• MRI/MRV (magnetic resonance venography): Map venous and lymphatic malformations and soft tissue/bony overgrowth without radiation.
• CT venography or catheter venography: Selected cases needing detailed anatomy before intervention.
• Genetic testing (tissue‑based): Mosaic PIK3CA variants may be identified from affected tissue; blood testing is often negative.
• Haematology work‑up: Baseline clotting risk, iron status if chronic bleeding suspected.
• Dermatology and orthopaedic assessment: Skin integrity, ulcer risk, shoe/orthotic needs, and limb length monitoring.

It is important to distinguish KTS from Parkes Weber syndrome. Parkes Weber features high‑flow arteriovenous fistulas, often with a palpable thrill or audible bruit; this requires different vascular management.

Treatment options and long‑term management

KTS requires a personalised, multidisciplinary plan. While there is no “cure,” targeted measures can substantially reduce symptoms and prevent complications.

Conservative measures

• Compression therapy: Graduated compression stockings or custom garments reduce oedema, improve venous/lymphatic return, and protect skin. Professional fitting is essential, especially for growing children.
• Skin care and ulcer prevention: Daily emollients, fragrance‑free cleansers, prompt treatment of eczema, careful nail/foot care, and protection from minor trauma.
• Physiotherapy and exercise: Calf‑muscle activation, low‑impact aerobic exercise (walking, cycling, swimming), and graded strength work support venous return and joint health.
• Pain management: Stepwise analgesia, topical agents, and addressing mechanical contributors (orthotics, footwear) improve function.

Medical therapies

• Anticoagulation: Considered in selected patients with DVT, high thrombotic risk, or peri‑interventional periods. Decisions are individualised in consultation with haematology/vascular teams.
• Targeted pathway inhibitors: In complex PROS phenotypes, sirolimus (an mTOR inhibitor) may reduce pain, lymphatic leak, and malformation activity under specialist supervision. Selected centres may consider PI3K inhibitors (e.g., alpelisib) for severe, refractory disease within protocols.
• Antibiotics: Rapid treatment of cellulitis; prophylaxis may be considered for frequent recurrences.

Procedures and interventions

• Laser therapy: Pulsed dye laser (PDL) can lighten capillary malformations (port‑wine stains) and reduce bleeding from superficial lesions.
• Sclerotherapy and endovenous ablation: Interventional radiology can target symptomatic venous malformations and varicosities to improve pain and ulcer healing.
• Lymphatic procedures: Selected microsurgical or interventional techniques may help refractory lymphatic leakage in specialist centres.
• Orthopaedic strategies: Epiphysiodesis (growth plate modulation), shoe lifts, and, rarely, debulking surgery to address limb length/girth differences and improve biomechanics.
• Surgery: Reserved for carefully chosen cases; risks and benefits are evaluated with a vascular/orthoplastic team due to bleeding/lymphatic considerations.

Living with Klippel–Trénaunay syndrome

Daily routines: Many people benefit from morning compression, scheduled movement breaks during desk work, leg elevation after prolonged standing, and meticulous skin care to prevent dryness and cracks. Choosing supportive footwear and avoiding tight straps at pressure points can prevent blisters and ulcers.

Sport and activity: Low‑impact endurance exercise supports circulation; impact or contact sports can still be possible with protection and medical guidance. Hydration and gradual warm‑up/cool‑down are helpful.

Travel: During long flights or car journeys, wear compression, mobilise every hour, perform ankle pumps, and consider medical advice on thrombosis prevention.

Pregnancy: Hormonal and volume changes may exacerbate symptoms. Pre‑pregnancy counselling with obstetrics and vascular teams is recommended; compression, skin care, and clot‑risk strategies are reviewed.

Mental health and support: Appearance changes, chronic pain, or care burdens can affect mental well‑being. Psychological support, peer groups, and practical adjustments at school/work are valuable.

Follow‑up and monitoring

KTS is dynamic across life stages. Children need periodic checks of limb length and gait; adults require surveillance for venous insufficiency and skin complications. After interventions, compression and skin care remain important. A named clinician coordinates care across dermatology, vascular, haematology, interventional radiology, physiotherapy, and orthopaedics.

Why choose Skinhorizon for Klippel–Trénaunay syndrome?

• Consultant dermatologist‑led care to diagnose the full spectrum of capillary, venous, and lymphatic changes and to coordinate referrals.
• Evidence‑based plans spanning compression, skin integrity, infection prevention, laser, and interventional options.
• Integrated monitoring for thrombosis, ulcer risk, and growth discrepancies, with access to vascular and orthopaedic partners.
• Family‑centred support for school, work, travel, and pregnancy planning, with clear safety advice.
• CQC‑regulated clinic with clear pathways for urgent review if complications arise.

Your first visit — what to expect

1. History: Birthmarks from infancy, limb size change, pain/swelling patterns, infections, clot history, mobility limits, and family goals.
2. Examination: Mapping of capillary/venous/lymphatic features; limb measurements; skin integrity; footwear/orthotic review.
3. Investigations: Ultrasound or MRI/MRV if needed; bloods where indicated; discussion of targeted genetic testing in specialist pathways.
4. Plan: Personalised mix of compression, skin care, physiotherapy, laser or interventional options, and safety netting for clots/infection.
5. Follow‑up: Timetabled reviews to track symptoms and limb metrics; rapid access for ulcers, suspected DVT, or cellulitis.

Reviewed by: Dr Mohammad Ghazavi, Consultant Dermatologist
Skinhorizon Clinic, 4 Clarendon Terrace, Maida Vale, London W9 1BZ
Last reviewed: 21 August 2025