Fax number: 210-963-8132

Skip to main content


Birthmarks. It seems as though most people have one. Most of the time, birthmarks are benign. True birthmarks are first noticed in the first few months after birth. They grow with the child. They become darker, bumpier, and even grow hair as the child becomes a teenager/adult. Birthmarks can be challenging. They can break all the rules. Remember the ABCDE's of Melanoma?

Birthmarks, however, can be asymmetric. They can have irregular borders and can be in various shades of brown. They come in all sizes and, not infrequently, are greater than the size of a pencil eraser. To top it off, they grow with the person. I just mentioned that they can change by becoming darker, bumpier, and grow hair as the person matures. They break, not one, not two, but ALL the rules.

So why do we have the ABCDE's of Melanoma? Because they apply to new moles. But not birthmarks.

No. Birthmarks follow their own rules. Birthmarks grow proportionately with the person. They keep the same shape. But just like a 3 foot boy becomes a 6 foot man, so does the 2cm birthmark become a 4cm larger birthmark. The man, now as an adult, has facial hair, so do many mature birthmarks. Now, as an adult, the man has rugged, weathered skin, so do mature birthmarks. Birthmarks grow up and look like larger, more developed versions of their former selves.

So, now that we've established that birthmarks don't follow the rules, what, you ask, tells me I'm looking at a birthmark? You do.

"It's been there ever since I can remember."

"Since you were 5 years old?"


"And it's always looked this way?"

"It used to be lighter, but it became more prominent & darker."

"In the last 6 months?"

"No. Over many years."

Whew! Birthmark.

"It's been there for many years."

"10 years?"


"Since you were a teenager?"

"No, I don't think so."

"In your 20s?"

"I'm not sure."

Hmmmm.... need to investigate this further. Several options here. You see, new moles can arise within the first 35 years of our life, so this could have been a new benign mole (which should follow the ABCDE's of Melanoma). But it is NOT a birthmark.

I'll never forget the day one of my patients came to see me with a large "birthmark" on his chest. "I've had it for many years." He couldn't tell me if he had seen it in childhood, though, and this was unsettling to me. "Ask your mother if she remembers it." Next time I saw him, he had a surprise for me. "She said she's never seen it before." WHAT?! Malignant Melanoma In Situ. He's doing well, by the way. He now has a scar on his left chest that wraps around to the back. But the simple thought that this (thin) melanoma had been sitting on his chest for decades was jarring to me (and him). He and I now laugh about it every time he comes in for a full body skin exam. But do not be fooled, skin cancer, and specifically melanoma, is no laughing matter.

So, parting thought: Know your moles. A simple short visit to a dermatologist can answer your question.

Dr. Sauceda Dr. Ana Trevino Sauceda, M.D., is a top-rated dermatologist serving patients of all ages throughout the San Antonio, TX and surrounding areas.

You Might Also Enjoy...