Capillary malformation (port wine stain)


Vascular malformations are skin lesions made of abnormally shaped, dilated blood vessels. Unlike vascular tumors (like hemangiomas), vascular malformations demonstrate normal cell turnover and growth. They are categorized based on the predominant blood vessel that is affected and further subdivided by the characteristics of blood flow through those affected channels.

The International Society for the Study of Vascular Anomalies (ISSVA) classifies vascular malformations into 4 broad groups:

  • Simple malformations
  • Combined malformations
  • Malformations of major named vessels
  • Malformations associated with other anomalies

Capillary malformations are simple malformations and the most superficial variant. They occur in 0.3% - 0.5% of the population, affecting boys and girls equally.


Capillary malformations are typically present at birth and demonstrate proportionate growth to that of the child. They can occur anywhere on the body but most commonly affect the head and neck, particularly the face. Capillary malformations present as pink or red marks on the skin. They may lighten slightly between the first and sixth month of life but eventually deepen in color. Over time, capillary malformations continue to darken and can thicken, developing a bumpy texture (vascular blebs). They are persistent and do not fade or go away as the child ages.


The diagnosis of capillary malformation is usually made clinically. Imaging studies like ultrasounds with Doppler or magnetic resonance imaging (MRI) may help to better define the skin lesion and exclude deeper involvement if the diagnosis is in question.


Capillary malformations are most commonly treated with a special type of laser. This may prevent the birthmark from darkening or thickening later on in life. Alternatively, if a family or patient desires, capillary malformations can be covered with make-up.