A port-wine stain (PWS) is a mark that is usually present at birth. It is made of enlarged blood vessels. This makes it appear as a reddish-purple patch of skin.


PWS is caused by a problem with the small blood vessels in the skin. Blood vessels can normally open and close to meet the needs of the skin. In PWS, the blood vessels stay open. Blood fills the vessels causing a purple color and raised skin. It may be due to problems with the nerves that control the blood vessels.

Risk Factors

There are no known risk factors for PWS.

Conditions associated with port-wine stains include:

  • Sturge-Weber syndrome
  • Klippel-Trenaunay-Weber syndrome


The marks vary in size. They are usually on the head or neck, but may be in other locations

Appearance may change over time:

  • In children—they are flat, red, or light purple
  • In adults—they are raised and purplish in color, darkening and thickening over time

They may be prone to bleeding when scratched.

PWS near the eyes may cause other problems as well.


PWS can be diagnosed based on a physical exam. In some rare cases, a skin biopsy may be done. An eye exam may also be done if the eye may be involved.

Skin Biopsy
Skin proceedure

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PWS is often harmless. They may occasionally result in dry skin. Moisturizing can help keep the skin healthy.

PWS may also cause emotional and social problems due to their visibility. Counseling may be considered.

If needed, treatment options include:


Laser treatment can destroy the blood vessels causing PWS. There are some risks with laser treatment. It may result in scarring and skin lightening or darkening.

Flash-lamp pumped pulse dye laser is one type used with PWS. Multiple treatments may be necessary.

Other Treatments

Blood vessels can also be shrunk or detroyed with freezing, surgery, and radiation. These treatments have had limited success. Lasers have replaced most of these treatments.


There are no current guidelines to prevent PWS.


American Academy of Dermatology

Vascular Birthmarks Foundation


Canadian Dermatology Association

Health Canada


Port wine stain. Nemours Kids Health website. Available at: Updated October 2016. Accessed December 27, 2018.

Port-wine stain information. Vascular Birthmark Foundation website. Available at: Accessed December 27, 2018.

Alster TS, Tanzi EL. Combined 595-nm and 1,064-nm laser irradiation of recalcitrant and hypertrophic port-wine stains in children and adults. Dermatol Surg. 2009;35(6):914-918.

Jasim ZF, Handley JM. Treatment of pulsed dye laser-resistant port wine stain birthmarks. J Am Acad Dermatol. 2007;57(4):677-682.

Last reviewed June 2018 by Michael Woods, MD  Last Updated: 12/27/2018