Melanonychia (mĕl′ə-nō-nĭk′ē-ə) 

n. Blackening on the nail plate by melanin pigmentation.

What It Is

As the sun takes its hold on its faithful worshippers this summer, sun seekers will keep their eyes on their skin. Those who know the dangers of the sun will be watching their skin, too — not in hopes of darker skin, but in hopes that their moles don’t change and signal something else, such as cancer. But in all this skin watching, who’s watching their nails for the same signs? If it’s not you, it should be.

Melanonychia is often a darkened band under or within the nail plate. Often, it runs vertically, and when it does, it’s referred to as longitudinal melanonychia or melanonychia striata.

Longitudinal melanonychia occurs on fingernails more than toenails, and it can simply be an area of hyperpigmentation (darker color), or it can be hyperpigmentation that accompanies subungual malignant melanoma — a fatal form of skin cancer.

According to Milady’s Standard Nail Technology, melanonychia “is present in all dark-skinned races.” A high percentage of African-Americans over age 50 exhibit melanonychia. The dark bands are also common in Latinos and Asians. But it is not common in Caucasians. Milady’s suggests that if seen, a malignant melanoma is a possibility.

And although the dangerous melanoma is much less common in African-Americans, when it does occur, it is disproportionately found in the hands and feet, including the nails. So, although the dark bands are common in African-Americans’ nails, techs should still be adamant about having their clients’ nails checked by a dermatologist if melanonychia is seen.

Symptoms

Melanonychia typically occurs vertically on fingernails, which is why it is called longitudinal melanonychia. It extends from the proximal nail fold/cuticle to the free edge.

“It looks like a black band in the nail,” says Dr. Richard K. Scher, a dermatologist at New York’s Columbia University specializing in nail care. “You could have the whole nail black, but that is more unusual. You could have two bands, but that is unusual as well.”

According to Scher the width can vary from 1 mm to several millimeters. “We worry more about the very wide ones than the very narrow ones,” says Scher.

Like the width of the darker bands, the color varies as well. “You have some that are very, very pale, and the individual may not even notice it,” adds Scher. “You have some that are jet black. The ones that are jet black are of more concern than the ones that are pale.”

Scher says the most common digits for melanonychia to appear on are the thumb, big toe, and the index finger.

The symptoms of melanonychia are all visible. “This is asymptomatic,” says Scher. “There is no pain, itching, or burning.”

Causes

Caused by a localized area of increased melanocytes (pigment cells), melanonychia becomes visible as the nail plate grows toward the free edge, says Milady’s.

There are a few outside sources that can stimulate the melanocytes. Certain medications, including chemotherapy, antibiotics, and anti-malaria drugs can cause hyperpigmentation to occur and cause the dark bands on clients’ nails.

Another cause could be trauma to the nail bed. “A traumatic event could stimulate the melanocytes in the nails,” Scher says. You can sometimes get post-inflammatory pigmentation from an allergic reaction (to nail products) or by a physical injury.

But medication and trauma are only rare causes of melanonychia, and it is generally unknown as to what usually causes the stimulation of the increased melanocytes.

Whatever has caused it, the melanonychia can be one of three things, says Scher: a melanotic macule (which is like a “glorified freckle”), a nevus (mole), or melanoma (cancer). Like the ones that appear on the skin, these changes are possibly related to sun exposure.

“We think the sun can have a negative effect on the nails as well as the skin,” Scher says. “We don’t see that as often because the nail plate filters out a third of the sun’s rays.”

How to Treat Them

“If the nail technician sees a discoloration in the nail, that person should be referred to a dermatologist immediately,” says Scher. “This is much different than some of the other findings a nail technician may observe.”

Although it may be common in your client’s race, or your client may tell you she has had the dark bands for a long time, you should still recommend she see a dermatologist anyway. Her dermatologist will most likely biopsy it to determine whether or not the melanonychia is benign (not of a current concern) or malignant (cancerous).  “Unless you look at it under a microscope,” Scher says, “there’s no guarantee that it is benign.”

After the melanonychia has been investigated, there is no actual way other than surgery to alleviate the appearance of its dark bands. It is believed that the melanonychia caused by medications will fade once medication has ceased, but there is no evidence to fully support that theory.

Considerations for Nail Techs

When you notice the melanonychia on the client’s nail, you can give the manicure or pedicure as you normally would, but avoid working on that one nail until she has seen a specialist. “It would be best not to do anything to the nail until after that person has seen his or her dermatologist,” says Scher. “It would need to be evaluated.”

If after seeing her dermatologist, it’s determined that the melanonychia is benign, it doesn’t mean that it will always be harmless. Much like a mole, the nail and the band should periodically be checked for changes. Therefore, you and the client should check it during every polish change. If she wears enhancements, soaking them off every few months and putting on a new set would be advisable. “Certainly the client or the nail technician or both should check the nail periodically,” Scher says. And the best way to see the changes is to see the bare nail. Any question or doubt about the change in condition, and the patient should return for another dermatology evaluation.