Klippel-Trenaunay-Weber Syndr... Health Article

Definition

Klippel-Trenaunay-Weber syndrome (KTWS) is most often defined by the presence of three classic characteristics: vascular abnormalities, prominent varicose veins or darkened skin patches, and limb enlargement.

Description

KTWS was first described by Drs. Klippel and Trenaunay in 1900. The condition is also known by the names Klippel-Trenaunay syndrome (KTS) and Angioosteohypertrophy syndrome.

Vascular abnormalities in KTWS may involve the capillary, venous, arterial, and lymphatic systems. Limb enlargement resulting in asymmetry of the limbs is quite common. This usually affects the lower limbs, but occasionally the upper limbs as well. Vein enlargement and varicose veins are also typically a part of KTWS. Other occasional abnormalities in KTWS may involve the fingers and toes, other skin changes, glaucoma, mental delays, seizures, and blood platelet problems.

Genetic profile

In most cases, KTWS occurs by chance alone. There is usually no family history and very little chance of the condition occurring again, even to the same parents. In 2004, researchers reported that abnormalities in the VG5Q gene on chromosome 5 were found to cause a susceptibility to KTWS. VG5Q is a gene known to be important for blood vessel development, so abnormalities within it might naturally lead to some symptoms of KTWS.

A few families with multiple people who may have KTWS have been noted. Ceballos-Quintal, et al., described a family with three people who were suspected to have KTWS, in three separate generations. Each person had different symptoms seen in KTWS. This family history suggests autosomal dominant inheritance in rare cases of KTWS. In dominant inheritance, an affected individual has a 50% chance of having an affected child with KTWS, regardless of that child's gender. It is also common to see families with histories of the condition in this type of inheritance pattern.

Demographics

KTWS is a relatively uncommon condition that is found worldwide, affecting males and females equally. Additionally, it appears to affect people of all ages, though the average age that children may come for medical care is four years.

Vascular abnormalities

Problems may occur as a result of an abnormal communication between a group of blood vessels and the skin. An abnormal grouping of blood vessels may reach the skin, causing the appearance of a large hemangioma on the skin. Additionally, the blood vessel walls may enlarge or swell, causing large, blood-filled spaces within the body. Internal bleeding can be a serious complication in some cases. There may also be swelling or masses of tissue from problems in the lymphatic system. These may disturb neighboring tissues and internal organs.

Veins and arteries may join abnormally, which can cause an improper flow of blood between the body's vein and artery systems. The deep veins can be incorrectly developed, sometimes being smaller than usual or even duplicated. Ultimately, this can disrupt the proper circulation of blood between various parts of the body.

Varicose veins are common in KTWS. People may have prominent veins that involve their feet or entire legs.

The lymphatic system, meant to help blood and fluid circulate, can be problematic in those with KTWS. Lymphatic fluid can collect abnormally, causing an enlargement and swelling of surrounding tissues. Smaller swellings can occur in various parts of the body like the neck, armpits, or other locations where the lymph nodes are naturally located.

Skin abnormalities

Abnormal capillary formations can cause dark patches on the skin, which look similar to a hemangioma. These are usually reddish in color and can be large. They are most often seen on the lower limbs, but in 17–21% of people with KTWS the entire limb or one side of the body is affected. The dark skin patches usually have an irregular and linear border to them. When seen on the torso of someone's body, they do not usually cross from the left to right sides. Other skin abnormalities can include smaller streaks and patches of dark skin.

Limb abnormalities

Limb enlargement is a very common sign of KTWS. In the vast majority of people, one leg is larger than the other. In others, an arm or a combination of both the arm and leg are affected. About 70% of people with KTWS have lengthening of an extremity, and an increase in thickness occurs in at least 50%.

Enlargement and vascular abnormalities usually occur together in the same limb. The enlargement of the limbs is presumed to be due to a combination of factors: underlying bone overgrowth, lymphatic swelling, muscle overgrowth, and thickened skin.

Other limb abnormalities can include enlargement of the fingers or toes, webbing between these digits, extra digits, or missing digits.