Subungual melanoma is a serious type of skin cancer that develops under your nail. It most commonly appears as dark brown or black streaks on your nail. Early detection and prompt treatment yield the best outcomes.
Subungual melanoma, or nail melanoma, is skin cancer under your nail. It usually appears as a dark, vertical (top to bottom) streak on your nail. Subungual melanoma is rare but serious. This type of skin cancer — called acral lentiginous melanoma — is an aggressive form of melanoma. Unlike other skin cancers, subungual melanoma isn’t linked to sun exposure. It’s most likely to develop in your big toe, thumb or index finger.
Cancer of the nail occurs in the nail matrix. The nail matrix is part of your nail bed (the pink tissue under your nails). It extends beneath your skin and contains nerves, blood vessels and lymphatic tissue. Unlike other cancers that begin on your skin’s surface, nail cancer begins in cells called melanocytes. Melanocytes produce melanin and give your skin its color. When these cells are activated, melanin production rises (called hyperpigmentation) and creates the vertical stripe that appears under your nail.
Many people assume discolored nails are from stubbing their toe or infection. Nail melanoma is often discovered later than other cancers because people don’t know the warning signs. Learning how to spot nail melanoma can help you get treatment as soon as possible. When subungual melanoma is caught early (before the cancer spreads), it’s more likely to have a successful outcome.
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Subungual melanoma usually has a distinct shape. Some may describe it as looking like you drew a line on your nail with a black or brown marker. It appears as a dark line on your nail and runs from bottom to top. This streak or stripe may start small but grow to cover the entire nail and extend to the cuticle (skin part of your nail). The discoloration can be irregular and be varying shades of blackish brown.
One colored line is typically less than 3 millimeters (about the size of two pennies pressed together) wide but can get wider over time. The lines can also multiply or grow. The widening of the line is more likely to occur at the bottom of your nail first. There are some cases where subungual melanoma doesn’t discolor the nail. Instead, a nodule (small, irregularly shaped growth) can develop and lift your nail, or other nail damage may occur.
Anyone can get subungual melanoma. However, you may be at a higher risk of developing melanoma under your nail if you’re between 50 and 70 years old and darker-skinned. It’s more common in people of African-American, Asian or Hispanic descent.
Subungual melanomas are rare and account for 0.7% to 3.5% of all melanomas worldwide.
The most common symptom of subungual melanoma is a discolored line that appears on your nail. It’s usually brown or black and runs from top to bottom (vertical). In some cases, the line can be irregularly shaped and increase in length and width over time.
If you have subungual melanoma, your nail may:
In some cases, discoloration of the nail doesn’t occur. That’s why it’s important to take note of anything that looks different or unusual about your nail. This is especially the case when you don’t recall injuring or damaging your nail.
Subungual melanoma can be mistaken for other nail conditions like nail infections or bruises. If you notice something under or on your nail, it’s always a good idea to check with your healthcare provider. Contact your healthcare provider if you see a nail that:
The cause of subungual melanoma isn’t fully understood. Medical experts know it’s more likely to affect older adults with darker skin. Unlike most melanomas, it doesn’t appear to be caused by sun exposure. Trauma or injury may be a risk factor. Other factors like genetics, biological family history or moles can play a role.
Subungual melanoma usually begins as a small, dark band under your nail. Over time, the discoloration can get wider and more irregular. There’s usually damage to the nail itself, like splitting or cracking. Advanced melanoma may begin to bleed.
It can take several months for nail melanoma to grow. It’s not something that develops overnight. You may notice it, then forget about it before noticing it again several weeks later.
Your healthcare provider diagnoses subungual melanoma after examining your nail and reviewing your medical history. They’ll determine if your nail area looks like subungual melanoma and if you’re at high risk for the condition.
It’s important not to dismiss issues with your nails as harmless. If you think something looks suspicious, it’s best to make an appointment with a healthcare provider.
Looking at the nail with the naked eye has its limits. It can be mistaken for other conditions or as an injury. For this reason, your healthcare provider may perform a dermoscopy or a biopsy.
A dermoscopy is when your provider examines your nail using a special microscope called a dermascope. This allows them to look at the area more closely and in greater detail.
A biopsy can give a definitive cancer diagnosis. It’s when a tissue sample from the area is tested for melanoma. Your healthcare provider will use a tube-like device to extract a small section of tissue to test for cancer.
Other tests may be performed to determine if cancer has spread to other areas.
Amputation used to be the standard treatment for subungual melanoma. It’s now the last resort.
The most common treatment for subungual melanoma is surgery. Your healthcare provider will surgically remove the melanoma and, likely, your entire nail.
Like other forms of cancer, nail melanoma can spread to other organs and tissues. Your healthcare provider may perform a sentinel node biopsy (examining the lymph nodes where cancer is likely to spread). They may also recommend immunotherapy, or other cancer treatments like radiation therapy to give you the best chance of success.
While the exact cause of nail melanoma is unknown, healthcare providers believe the following factors can increase your risk:
It's hard to prevent subungual melanoma because it's not directly caused by the sun or by using harmful substances. Your best option for prevention is to be aware of it and to check your nails for signs of discoloration or unusual damage.
Yes, subungual melanoma can spread, especially to the skin around your nail. Therefore, it’s important to note any unusual changes in your nail or surrounding skin. Early detection is the best way to stop subungual melanoma from spreading.
The survival rate is high when subungual melanoma is detected early. Survival rates are about 95% when it’s caught at an early stage and treated quickly. If subungual melanoma is diagnosed later and cancer has spread, the survival rate can be as low as 15%.
If you’ve been diagnosed with nail melanoma, it’s natural to have questions. Some questions you might ask are:
A subungual hematoma is when blood gets trapped under your nail. It usually happens after an injury or from poorly fitting shoes. Subungual melanoma appears as dark lines, while hematomas look more like a dark bruise or smudge under the nail. Blood may grow out or appear when you cut your nails if it’s a hematoma. Hematomas appear quickly or within hours of injury. Melanoma grows more slowly.
There are times when nail cancer can resemble a hematoma. If you’re unsure or notice anything odd under your nail, it’s best to contact a healthcare provider.
Knowing the signs of subungual melanoma is the best thing you can do for this type of skin cancer. Call your healthcare provider if you notice a dark line or other change to your nail. Most people recover when melanoma is diagnosed and managed early. If you have subungual melanoma, talk to your healthcare provider about treatment and what to expect. Your providers are there to help get you through this challenging time and listen to your concerns.
Last reviewed by a Cleveland Clinic medical professional on 01/02/2024.
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