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Plastic and Reconstructive Surgery

Complex Combined Malformations

The complex combined type of vascular malformation is often associated with both soft tissue and skeletal overgrowth. These malformations can include a capillary component (on the surface of the skin), lymphatic, venous, and/or arterial components.  Klippel-Trenaunay Syndrome (KTS) is one type of complex combined vascular malformation.  Children with KTS are seen at the KTS Clinic at SickKids.  

Klippel-Trenaunay Syndrome

I Diagnosis I Treatment I Frequently Asked Questions 


Klippel-Trenaunay Syndrome (KTS) is a slow-flow complex combined vascular malformation where capillary, venous and lymphatic malformations occur in association with increased growth (enlargement) of the affected body part.  Most commonly, KTS occurs in one leg although it can affect the abdomen, chest, arms or several body parts.  

The capillary malformation affects the skin causing a red-coloured vascular skin stain, often called a port wine stain.  Abnormalities in lymphatic flow and lymphatic malformations may be seen.  Small lymphatic spots (called lymphatic vesicles) can occur on the surface of the port wine stain.  

Left: Port wine stain in the skin in Klippel-Trenaunay Syndrome (KTS) with small bleeds on the surface of the stain. Right: The port wine stain in this KTS case is much paler.

Venous malformations occur frequently as varicose veins (often on the outside of the leg).  Sometimes the deep veins in the body may be partially absent.  Over many years, the varicose veins become more obvious.  There is an increased risk of infections and blood clots in KTS which can cause pain.  Bleeding can sometimes be troublesome in the skin and other possible affected locations such as the bowels.  

Enlarged veins on the outside of the leg (arrow) are present in addition to the port wine stain in the skin.

KTS is associated with increased growth of the affected body part.  For example, when an arm or leg is affected in KTS an increase in the length as well as the circumference can be seen.  When KTS affects a leg, yearly measurements of leg growth are made.  If the measurements suggest that after several years there will be a significant difference in the lengths of each leg, orthopedic surgery may be required to correct the leg length difference.  In most patients, when KTS involves an arm or leg, it is likely that the affected arm or leg will have reasonably good function.

Affected leg is enlarged. There is a port wine stain affecting some of the skin of the leg (arrow).


The diagnosis of KTS is based on physical examination.  Some investigations such as an MRI scan, blood tests looking for blood clotting and venograms (a study where radiological dye is injected to look at veins) may be needed.  


Most patients with KTS do not require invasive (surgical or radiological) treatments.  In patients with an affected extremity, a compression garment is often recommended.  This can help reduce some of the leg swelling, improve return of blood from the veins and reduce ‘a heavy feeling’ in the leg experienced by some patients.

A few patients with KTS require specific treatments such as antibiotics for infections, blood thinners for blood clots, orthopedic surgery for leg growth correction and surgical or radiological treatment for the varicose veins, venous malformations and lymphatic malformations.  

Frequently Asked Questions

What is the difference between a venous malformation and KTS?

KTS is a vascular anomaly (birthmark).  This syndrome is a complex combined slow flow vascular malformation which most commonly affects a leg.  It has 3 components: a port-wine stain (a capillary malformation) in the skin, varicose veins (a type of venous malformation) and increased growth of bone or soft tissue.  An abnormality of lymphatics may or may not be present.  

A venous malformation is also a slow flow vascular malformation and is one component of Klippel-Trenaunay syndrome.  A venous malformation can occur on its own, independently of Klippel-Trenaunay syndrome.  

Why can’t the vascular malformations present with Klippel-Trenaunay syndrome be surgically removed?

KTS is made up of several different vascular malformations in addition to the increased growth of tissue and bone.  The venous malformations in a few patients (for example, those with small malformations just under the skin) may be treated surgically.  For most patients with KTS, surgical removal of the venous and lymphatic malformations may be difficult and not a safe option.  A few patients may be suitable for invasive treatments using radiological and surgical approaches.  

What do compression garments do?

Compression garments provide external support to the affected arm or leg and reduce the amount of blood pooling (venous congestion) in the affected area.  In cases where there is a lymphatic component, compression garments also reduce the amount of swelling (edema) in the affected area.  

How will I know the compression garments are working?

To see the benefits of wearing a compression garment, the garment must be worn consistently and daily for a few months.  It maybe advisable to gradually build up the length of time the garment is worn, in order to ensure tolerance of the garment.  If you have concerns regarding the fit of the garment, please contact the physiotherapist and the garment fitter within two weeks of receiving the garment.  

Wearing a compression garment can significantly reduce the swelling and heavy feeling in patients with KTS where an affected arm or leg is enlarged.  

I find the cost of continuously purchasing compression garments very expensive.  What should I do?

Your insurance company may cover part or all of the cost of your compression garment and will likely require that a prescription be provided to them.  A compression garment is a medical device and your doctor at SickKids will provide you with a prescription for this.  The physiotherapists at the KTS Clinic can provide you with information about other potential sources of financial help, such as the Ontario Assistive Devices Program (ADP).  

Why does Klippel-Trenaunay syndrome cause pain?

Infection, blood clots and bleeding in the affected body part can cause pain.  Some patients experience a particular type of neurological pain called neuropathic pain.  

Is Klippel-Trenaunay syndrome associated with an increased risk of blood clots?

Yes, because Klippel-Trenaunay syndrome has a venous component where blood usually flows slowly, it can be associated with an increased risk of blood clots.  Somewhat surprisingly, it can also be associated with an increased risk of bleeding.  To prevent this increased risk from turning into complications, it is important that you come in for regular follow-up appointments the clinic.  Wearing a compression garment as prescribed can decrease the risk of complications.  

What are the complications of blood clots?

A new blood clot may grow or move through the circulation.  In the first case, growth of the blood clot may cause a total block of blood flow in the affected region, causing increased size, temperature, and progressive pain and change of colour in the affected body part.  If the clot continues to grow, the end of the blood clot may become big enough that it may break and may be carried by the blood circulation elsewhere (embolism).  The piece of the blood clot being carried by the circulation may cause problems at areas that are vital such as the lungs, heart and even the brain.  

Is it possible to treat patients with blood clots?

Yes.  The best treatment for these potentially serious and even life threatening complications is prevention.  It is therefore important for you to come to regular clinic appointments so the clinic team can examine you and obtain blood tests that will help decide your risk of blood clots.  In case a blood clot occurs, there are medications called anticoagulants which can help preventing clot growth or movement.  There are also other treatments that your physician at clinic may discuss with you.  

What should I do if I notice that a leg length difference is becoming more apparent?

This will be assessed during the yearly clinic visit.  It is very important that you attend clinic every year to measure your leg lengths and to be followed-up.  The doctors and physiotherapists at the clinic may recommend a shoe lift or a referral to an orthopedic surgeon.  

Is Klippel-Trenaunay syndrome considered a disability?  (Do I qualify for disability benefits or services?)

KTS may or may not be considered a disability.  This is evaluated on an individual basis.  

What can I do to deal with my Klippel-Trenaunay syndrome at school?

If your Klippel-Trenaunay syndrome affects your ability to write or use a keyboard or move between classes in the allotted time, it is encouraged that you speak to someone at your school about this.  A school may make arrangements to accommodate you and may require a medical note.  

After the age of 18, where are patients with Klippel-Trenaunay syndrome treated?

When you reach 18 years of age, if your care needs to be continued, the clinic will arrange transfer of care to an adult clinic in Toronto.