Melanoma can look like nail fungus: Woman's Facebook warning goes viral

A young woman in England is hoping to save lives by sharing her story of a sneaky case of skin cancer that could have been mistaken for nail fungus.

"See that on my thumb? Do you know what it is? It's skin cancer," Melanie Williams wrote in a Facebook post that has been shared more than 100,000 times. She said the black mark under the nail on her thumb "grew from nothing in a matter of weeks. I thought it was just a fungal infection or a wart. Sadly not."

Williams said she's "lucky" because the cancer was caught early and hadn't spread. Even so, she had to undergo surgery last week to amputate part of her thumb.

"I don't want your sympathy, I want more awareness," she writes. "Please go and get any changes or growths on your skin checked out, please tell people around you to get checked as well. Don't leave it to chance or make excuses!"

In an update posted Thursday, Williams said she will be getting more tests done this week, and may need additional surgery to remove more of her thumb. Still, she knows the outcome could have been much worse if she hadn't gone to the doctor and gotten it checked when she did: "I will be fighting fit in no time but if I'd left it, I may have been losing more than a thumb."

Melanoma is the deadliest form of skin cancer, claiming about 9,000 lives in the U.S. each year. The American Academy of Dermatology says it can almost always be treated successfully if caught early enough. The organization urges people to check their skin regularly for signs of cancer, including areas like fingernails they might not think are vulnerable: "Check your scalp, palms, soles, fingernails, and toenails. Melanoma can appear under a nail. Beneath a nail, the most common early warning sign of melanoma is a brown- to black-colored nail streak."

When checking your skin, experts say look out for the "ABCDE's of melanoma," telltale signs that a mole could be cancerous. The acronym stands for:

A -Asymmetry: A mole that is uneven in shape and color.

B -Border: Melanomas have an irregular, scalloped or poorly defined border.

C - Color: Varies from one area to another; shades of tan and brown, black; sometimes white, red or blue.

D -Diameter: Melanomas are usually greater than 6mm across (the size of a pencil eraser) when diagnosed, but they can be smaller.

E -Evolving: A mole or skin lesion that looks different from the rest or is changing in size, shape or color.

Suspicious growths should get checked by a dermatologist.

The U.S. Centers for Disease Control and Prevention says more than 90 percent of melanoma skin cancers are due to UV radiation exposure from the sun, and offers some simple advice for prevention: "Protect yourself from the sun by wearing a hat and clothes that cover your skin. Find some shade if you're outside, especially in the middle of the day when the dangerous rays from the sun are most intense, and apply broad-spectrum sunscreen," CDC director Dr. Tom Frieden said in a recent statement.