How to know if skin cancer might be lurking under your nails

Expert: 1 percent of melanomas happen under or around the nail

When Peggy Waters’ thumbnail split open, she didn’t think much of it.

“I just put a Band-Aid down around it to to pull the two sides together,” she said.

Fast forward a year and a half, and she was being treated for melanoma under her nail.

It’s rare, but it happens.

“About one percent of all melanomas occur under and around the nail, and it varies a bit by ethnicity," Dr. Phoebe Rich explained. "The darker your skin, the fewer melanomas you have in general, but the more likely they are to occur under and around the nail.”

Rich said nail melanomas are generally painless, which is a problem, because people aren’t aware anything is happening. There are signs to look for, though.

“The most common sign is a pigmented stripe in the nail," Rich said. "It starts as a brown or black or even gray band in the nail that starts at the cuticle and runs out to the free edge of the nail.”

Or, the nail may split -- like Waters' did. By then, the melanoma might have spread.

What are the risk factors?

“UV light and sunburn plays very little role. What's more important is family history," Rich said. "They generally occur in people over age 50, although we see them in all age groups.”

A history of nail trauma is also a factor. The most common digits to get melanoma are the thumb and big toenail.

“If you diagnose them early and get them off early, there's a very very good chance of cure. But if you let them go and they remain undetected and undiagnosed, they're almost always fatal,” Rich explained.

Treatment might include removing the nail  or, in extreme cases, taking off the finger or toe tip.

Melanomas can be diagnosed during an exam with magnification and special polarized light, and in some cases, a biopsy.

Waters said she’ll never wait again if she sees an issue with her nails. 

“If I see something strange that's happening on my skin, I get it checked immediately," she said.

It’s important to have regular examinations with a dermatologist and point out any changes in your nails.