Q: My son (age 7) has a dark birthmark on his back that I think he’s had all his life. His doctors have looked at it in the past and all have said it appears to be normal, but it keeps getting larger as his body grows bigger. 


A: Birthmarks come in a variety of colors, shapes, locations and can change over time. There are two main types of birthmarks, vascular and pigmented. Vascular birthmarks can be flat or raised. Flat vascular birthmarks, sometimes referred to as port-wine stains, can be reddish or purplish, fade with time, but can also appear to grow as a child’s body grows. 

Raised vascular birthmarks can be flesh-colored, reddish-purplish or even bluish if they’re deeper in the skin layers. These raised vascular birthmarks have a tendency to grow over the first 1 to 2 years of a child’s life but then begin to slowly regress.

Pigmented birthmarks, also called moles or nevi, come in a variety of sizes, textures and colors. 

They may be flat and brown or dark blue or green stained. Flat pigmented birthmarks may fade over time, but may also appear to grow as a child’s body grows. 

Larger nevi may have a variety of brown or dark pigmentation within the same birthmark. And they may be raised and/or covered with hair. These also may grow as a child’s body grows, but should be followed by a dermatologist. 

Birthmarks may also be associated with other serious health conditions and should be evaluated by clinicians carefully — both when initially noted and over time to monitor any changes.