Port Wine Stain on a limb can be either isolated or associated with complications (venous or orthopedic impairment, arteriovenous malformations), leading sometimes to complex syndromes (Klippel-Trenaunay syndrome,Parkes-Weber syndrome).

Little is known about epidemiology of port wine stains: their evolution during the growth of the child, the frequency of complications, genetic data, and prognostic factors.

This prospective french national cohort will help for : description of the evolution of port wine stain and possible complications; prognostic factors for complications ; association with mutations of RASA1 gene; quality of life of these children. It will also help for global appreciation of the management of this disease in France.

Prospective national study, including 16 Pediatric and Dermatologic Departments.

Methods : each children with a port wine stain on a lower limb will be followed up for 5 years.

Collected data : demographic data, clinical features, alterations of RASA1 gene, vascular evaluation by ultrasonographic and orthopedic evaluation by X rays, quality of life with a questionnaire.

Inclusion period = 3 years Follow up period = 5 years Population = 150 children

Inclusion Criteria:

• Child between 2 and 12 years old with a port wine stain on a lower limb ( or two lower limbs) with national health assurance with consent from one parent

Exclusion Criteria:

• child with orthopedic impairment with no link with the port wine stain