This Specific Fingernail Mark Could Be a Melanoma Symptom

Don't brush off this easy-to-ignore symptom of skin cancer.

What your nails might be telling you about your skin cancer risk

When you think of skin cancer, you probably think of checking head to toe for moles. But did you know your nails can also reveal an important sign of melanoma? With the American Academy of Dermatology (AAD) reporting that one in five Americans will develop skin cancer in their lifetime, it’s crucial to know any little change that could be a warning sign.

Manicurist Jean Skinner has firsthand experiencing catching this stealthy symptom. “I had a walk-in nail client a couple of weeks ago,” she wrote in a Facebook post. “She had a straight dark vertical stripe down her nail. She said as soon as she sat down—I need a color dark enough to cover this stripe.”

Other salons had speculated that the woman’s mysterious line could be due to a calcium deficiency, a blood blister, or a strange hereditary mark. Yet Skinner knew better and was concerned. She immediately told her customer that the dark line was likely a symptom of melanoma.

Subungual melanoma (aka nail melanoma) is, as its nickname suggests, a skin cancer that occurs under the nail. It affects 0.7 to 3.5% of people with melanoma, according to the Journal of the American Academy of Dermatology. Though subungual melanoma is an uncommon type of skin cancer, it’s important to know about its telltale sign: a dark black or brown line across a finger or toenail, according to the AAD.

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close up of a bit toe with a black stripe; nail melanomaCourtesy AIM at Melanoma Foundation

Skinner’s hunch was correct—and unfortunately the prognosis wasn’t good. The client called later to tell her she had aggressive melanoma that had spread to her lymph nodes.

A black band isn’t the only skin cancer symptom that could be hiding under your nail polish. Other signs of nail melanoma include darkened skin around the nail and cuticle, blood, pus and splits in the nail,  the AAD says.

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More skin cancer symptoms to look for

In addition to checking your fingernails for dark marks, you should do your own skin self-exams to check for irregular moles. See your dermatologist if you see any moles that exhibit any of the ABCDEs of melanoma:

  • Asymmetry
  • Irregular borders
  • Varied color including shades of tan, brown, black, white, red or blue
  • A diameter of 6mm or more
  • Evolving size, shape or color

According to the Skin Cancer Foundation, melanoma is almost always treatable when detected early, but if left alone it can spread to other areas of the body where it can be potentially life-threatening. While melanoma is not the most common type of skin cancer, it does cause the most deaths.

As with other skin cancers, early diagnosis of subungual melanoma is crucial. See your doctor right away if you happen to notice a dark mark under your fingernail or any other suspicious symptoms. Your doctor or dermatologist can do a biopsy to determine if the irregular growth or discolored area is a sign of skin cancer.

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Sources
Medically reviewed by Joshua Zeichner, MD, on October 29, 2019

Miranda Manier
Miranda is the Associate Editor for TheHealthy.com and The Healthy section of Reader's Digest magazine. Previously, Miranda was a producer at WNIT, the PBS affiliate in South Bend, Indiana; and the producer in residence for Minneapolis TV news KARE 11, where she won an Upper Midwest Regional Emmy Award for producing gavel-to-gavel coverage of the Derek Chauvin trial. Miranda also interned at Chicago’s PBS station, WTTW, and worked as the managing editor at the Columbia Chronicle at Columbia College. Outside of work, Miranda enjoys acting, board games, and trying her hand at a good vegan dessert recipe. She also loves talking about TV—so tell her what you’re watching!