Klippel–Trénaunay syndrome

Klippel–Trénaunay syndrome, formerly Klippel–Trénaunay–Weber syndrome and sometimes angioosteohypertrophy syndrome and hemangiectatic hypertrophy, is a rare congenital medical condition in which blood vessels and/or lymph vessels fail to form properly. The three main features are nevus flammeus (port-wine stain), venous and lymphatic malformations, and soft-tissue hypertrophy of the affected limb. It is similar to, though distinct from, the less common Parkes Weber syndrome.

The classical triad of Klippel–Trenaunay syndrome consists of:

vascular malformations of the capillary, venous and lymphatic vessels;

varicosities of unusual distribution, particularly the lateral venous anomaly; and

unilateral soft and skeletal tissue hypertrophy, usually the lower extremity.

It belongs to the PIK3CA-related overgrowth spectrum of diseases which are caused by mutations in the PIK3CA gene.

Signs and symptoms

The birth defect is diagnosed by the presence of a combination of these symptoms (often on approximately 1⁄4 of the body, though some cases may present more or less affected tissue):

One or more distinctive port-wine stains with sharp borders

Varicose veins

Hypertrophy of bony and soft tissues, that may lead to local gigantism or shrinking, most typically in the lower body/legs.

An improperly developed lymph system

In some cases, port-wine stains (capillary port wine type) may be absent. Such cases are very rare and may be classified as "atypical Klippel–Trenaunay syndrome".

KTS can either affect blood vessels, lymph vessels, or both. The condition most commonly presents with a mixture of the two.