Toenail melanoma is a rare cancer that develops underneath the fingernail or toenail. You can also get toenail fungus from the overgrowth of fungi in, under, or on the nail. The two conditions can look similar, but toenail fungus is more common.

Toenail melanoma is another name for subungual melanoma, which means “under the nail.” Toenail fungus is also called onychomycosis.

Keep reading to learn more about subungual melanoma, differences from toenail fungus, and the symptoms, causes, and treatment for both.

Melanoma is a type of skin cancer. Subungual melanoma is uncommon. It accounts for only 0.7%–3.5% of all malignant melanomas worldwide. This form of melanoma occurs in all racial groups, but it is more common in People of Color.

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.

The 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.

Read on to learn about how doctors diagnose subungual melanoma vs. nail fungus.

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 the following:

Subungal melanoma and nail fungus have different causes.

Causes of subungual melanoma

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

  • a family history of melanoma
  • old age
  • being a Person of Color

Causes of nail fungus

With fungal nail infections, some usual main causes are:

  • mold
  • 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 nail cancer 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 life threatening, but the 5-year survival rate for subungual melanoma can vary dramatically depending on how early the cancer is identified. It can range from 15%–97%.

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

Read on to learn how doctors treat nail fungus vs. subungual melanoma.

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 an antifungal skin cream
  • washing your hands and feet regularly and keeping them dry

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 for making a definitive diagnosis. A dermatologist or nail specialist will remove some or all of the nails 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.

See your doctor immediately if you have a fungal nail infection and possible subungual melanoma symptoms.

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 have toenail fungus or subungual melanoma.