Originally Posted by jpuritz
the PWS on my arm disappears when pressure is applied and reappears when the pressure is relieved. However, does any have a birthmark that changes color with the temperature? Mine becomes purple when I'm cold and a light pink when I'm feverish.
I have PWS on left side of my face and since childhood I have noticed it changes colors with my body temperature.
In normal temperature, it is light red in color. When I am cold (after swimming/ going out in winter ), it becomes very dark.. blackish red in color.
After good amount of physical activity like gymming (when my body temperature increases) it again becomes dark, but not as dark as it is when I am cold.
I could think of these reasons for color change.
When cold, blood in the vessels must be getting thicker like a blood clot (darkening of the birthmark seems similar to what we see when the blood clots) .
When body temperature increases, blood flow in that area must be increasing, causing it to change the color.