Toenail melanoma is another name for subungual melanoma. It’s an uncommon form of skin cancer that develops underneath the fingernail or toenail. Subungual means “under the nail.”

Toenail fungus is a more common condition that occurs from the overgrowth of fungi in, under, or on the nail.

Keep reading to learn more about subungual melanoma, including how to tell it apart from toenail fungus, along with symptoms, causes, and treatment for both.

Melanoma is a type of skin cancer. Subungual melanoma is uncommon. It accounts for only 0.7 percent to 3.5 percent of all malignant melanomas worldwide. This form of melanoma occurs in all racial groups, with 30 to 40 percent of cases appearing in non-white people.

Subungual melanoma is rare, but it is deadly if left untreated. One of the biggest challenges with treating subungual melanoma is diagnosing it early and correctly.

It’s often difficult to diagnose because this type of cancer often has a dark brown or black streak on the nail that’s similar in appearance to other benign causes. These causes include:

  • injury to the nail with blood under the nail
  • bacterial infections
  • fungal infections

There are, however, symptoms to look out for that can make diagnosis easier for your doctor.

Diagnosing subungual melanoma

A diagnosis of subungual melanoma is uncommon and difficult to determine. Here are certain warning signs to look out for:

  • brown or black bands of color that increase in size over time
  • change in skin pigment (darkening around the affected nail)
  • splitting nail or bleeding nail
  • drainage (pus) and pain
  • delayed healing of nail lesions or trauma
  • separation of the nail from the nail bed
  • deterioration of the nail (nail dystrophy)

Diagnosing toenail fungus

If you have nail fungus, some symptoms that differentiate from melanoma include:

Causes of subungual melanoma

Unlike other forms of melanoma, subungual melanoma doesn’t appear to be related to an overexposure of the sun’s UV rays. Instead, some of the causes and risks of developing this cancer include:

  • a family history of melanoma
  • old age (increased risk after age 50)

Causes of nail fungus

With fungal nail infections, the main cause is typically

  • molds
  • dermatophyte (a common type of fungus called that can be easily picked up by your hands or feet)

Certain behaviors and preexisting conditions that can affect your risk of nail fungus include:

There are many overlaps between nail fungus and nail cancer. Since it’s easy to mistake cancer of the nail for a fungal infection, you should see a doctor immediately to get a definitive diagnosis.

See a doctor immediately if you suspect you have toenail fungus or subungual melanoma.

Since the prognosis of subungual melanoma gets worse the longer it takes to diagnose, it’s better to be safe and get any possible symptoms checked out and cleared as soon as they appear.

Fungal infections are not considered life-threatening, but the 5-year survival rate for subungual melanoma can vary dramatically depending on how early the cancer is identified. According to the Canada Dermatology Association, chances of recovery can range anywhere from 16 to 80 percent.

If you wait too long for diagnosis and treatment, there’s a risk of the cancer spreading throughout the body’s organs and lymph nodes.

Diagnosis and treatment of nail fungus

If you have nail fungus, treatment is relatively straightforward. Your doctor will commonly recommend:

  • taking medication, such as itraconazole (Sporanox) or terbinafine (Lamisil)
  • using antifungal skin cream
  • washing your hands and feet regularly and keeping them dry

Diagnosis and treatment of subungual melanoma

Diagnosing and treating subungual melanoma is much more involved.

Once your doctor performs the initial assessment and determines you might have subungual melanoma, they’ll commonly suggest a nail biopsy.

A nail biopsy is the primary diagnostic tool available for making a definitive diagnosis. A dermatologist or nail specialist will remove some or all of the nail for examination.

If there’s a diagnosis of cancer, depending on the severity and how early it was found, treatment can include:

Subungual melanomas are difficult to diagnose because they’re rare and can appear similar to other common afflictions of the nail, such as fungal and bacterial infections.

If you have a fungal nail infection but are also exhibiting possible symptoms of subungual melanoma, see your doctor immediately.

Since early detection is crucial to a positive prognosis, it’s important to be proactive in examining your nails for any signs of melanoma. Don’t hesitate to see a doctor if you think you might have either toenail fungus or subungual melanoma.