Yes, melanoma can affect a fingernail or toenail, and there are two major warning signs that what you see is a potentially deadly tumor — also known as subungual melanoma.
Myths About Nail Melanoma
• White people can’t get it. Wrong, whites can get this disease, though it’s much more common in blacks and Asians.
• Children can’t get it. Wrong. There are cases of pediatric subungual melanoma.
• Since it affects only the nail, it’s not that serious. Wrong. Like any other kind of melanoma, a tumor that affects the nail can penetrate and spread to other parts of the body via the lymphatic system.
Once this disease has spread to distant sites, prognosis is very poor.
Between one and two percent of all melanomas are the subungual type.
“I routinely see patients in for streaks or dark spots in the nails,” says Erum Ilyas, MD, a board certified dermatologist who performs adult and pediatric medical dermatology, cosmetic dermatology and skin cancer treatment with Schweiger Dermatology Group.
“It goes without saying that if you google this one, you will undoubtedly see that this needs to be evaluated to rule out melanoma,” says Dr. Ilyas.
Two Big Warning Signs of Nail Melanoma
Hutchinson’s sign. “The Hutchinson’s sign is when the pigment in the nail extends to the nail fold (the skin next to the nail),” says Dr. Ilyas. “This sign is considered ominous for a melanoma of the nail.”
Hutchinson’s sign. The pigment is “leaking” into the skin near the cuticle.
What’s even scarier is that a benign pigment in the nail bed (yes, harmless moles can appear there and take on the shape of a streak, band or line) can create a “pseudo-Hutchinson’s sign.”
To a layperson, this appears to be a true Hutchinson’s sign. But a dermatologist knows what to look for that would indicate a benign finding.
Nevertheless, if you see what seems to be the Hutchinson’s sign – get to a dermatologist.
Progression and evolution. Dr. Ilyas explains, “Pigment or color that extends or spreads over time is concerning for a melanoma.”
The obvious progression in this case is the destruction of the top corner of the nail — which is right above an obvious Hutchinson’s sign. Ann Dermatol. 2018 Feb;30
It is not uncommon for people to present with a benign pigmented streak of the nail.
“These tend to have clear defined edges, not extend to the nail fold, and stay stable,” says Dr. Ilyas.
“If the color of this streak starts to become hazy along the edges or darker over time, this can be suspicious for a cancer and should be evaluated.”
Subungual Melanoma: Exact Location of Tumor
The tumor is not literally IN the nail – that part of the finger or toe that you trim or paint.
The cancer is actually underneath the nail, in the matrix, and it shows through the nail.
Dr. Ilyas is the founder of the AmberNoon line of fashionable sun-protective clothing.
Lorra Garrick has been covering medical, fitness and cybersecurity topics for many years, having written thousands of articles for print magazines and websites, including as a ghostwriter. She’s also a former ACE-certified personal trainer.
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