Melanoma is a serious type of skin cancer, and one of the unusual places it may originate is the skin under the toenail. Most common in people with dark skin, toenail melanoma can affect any nail on the foot. Indications that a toenail is affected by melanoma include a dark spot or streak on the nail, or an uncolored growth under the nail.
Healthy skin contains melanocyte cells that produce a substance called melanin, which is responsible for the variation in skin tone of different races of people. It is a pigment, which means it gives color to a tissue, in this case, a brown color. Sun exposure in paler people triggers an increase in melanin production, which darkens the skin as a defense against ultraviolet damage from the sun's rays. When this defensive mechanism becomes damaged, perhaps through excessive sun exposure, the melanocytes, which are dark from melanin stores, grow out of control.
Three different types of cancer can cause a toenail melanoma. Most commonly, it is due to acral lentiginous melanoma, but nodular melanoma or desmoplastic melanoma may also be responsible. Whatever the exact cause, any cancer that occurs in the nails is called subungual melanoma. Basically, this is an overgrowth of melanocytes in the tissues relating to the nail.
People with the condition may notice an abnormal coloration on their toenail. Commonly, a dark spot on the nail appears, which may be brown, black or purple. The cancer may look identical to damage caused by injury to the nail, so a person with it may not immediately spot the significance of the nail coloration. Often, the dark coloration appears as a streak that can stretch vertically down the nail.
Toenail melanoma does not always involve colored nail spots, and often the condition appears simply as a lump under the nail. The growth of the melanocytes can split the nail, or raise it up from the skin underneath. Generally, the cancer does not produce pain in the toenail area, but the cells may bleed or weep.
As the toenail that is most affected by toenail melanoma is on the great toe, scientists think that physical trauma to the nail may increase the risk of this type of melanoma developing. Possible treatment options include surgical removal of the cancer, amputation of the toe, or chemotherapy. Toenail melanoma is relatively uncommon in light-skinned people, but is responsible for up to half the cases of melanoma in people of African or Asian descent. Famed musician Bob Marley's cause of death was melanoma that began in the toenail.
Is It a Bruised Toenail or Melanoma?
It can be difficult to tell the difference between a bruised toenail and melanoma. The only way to determine whether a bruised toenail is actually melanoma is through a doctor’s assessment.
Some patterns are more indicative of melanoma than others. For example, a defined, dark line from the cuticle to the tip of the nail is more likely to be melanoma. This type of mark is called “Hutchinson’s sign.”
How Is Toenail Melanoma Diagnosed?
Healthcare providers often use the “ACBDEF method” to determine whether the marks near your toenail are cancerous and require a biopsy.
A is the age of the patient. Those who are older than 50 are more likely to develop melanoma. B is the presence of bands and their characteristics; black or brown bands are more indicative of melanoma, and blurred edges around the bands are also a telltale sign. C stands for change: Since it was first detected, has the discoloration become darker or larger? D means which digit is affected as the riskiest nail is the big toenail. E represents extension as in whether the discoloration extended to the surrounding area. Finally, F is for family history, as melanoma is more likely in those who have relatives that have suffered the same condition.
If your doctor suspects the bruise may be cancerous, he or she will take a biopsy of the tissue. Drilling or punching through the nail is done to obtain this sample. A local anesthetic is used before this is performed.
What Are the Symptoms of Melanoma on a Toenail?
Skin that appears darker than usual next to a toenail is the primary symptom of melanoma. Other symptoms may include:
- Black, brown, or purple patches, lines, streaks, spots, or marks
- A nail that disconnects from the nail bed without any physical injury
- Splitting or cracking nails
- Bleeding from the toenail
- A raised area or bump in the toenail
If the melanoma is newer, you are unlikely to feel any pain unless the nail is lifted from the nail bed. However, if cancer develops and spreads to the bone, you might experience more intense pain.
What Causes Toenail Melanoma?
Other melanomas can be caused by overexposure to the sun, but toenail melanoma’s causes are unknown and unrelated to sun exposure. This type of melanoma originates from the proliferation and activation of the melanocytes that produce melanin. Some doctors believe that damage to the nail or toe can cause toenail melanoma.
While often described as “toenail melanoma,” cancer only affects the skin near, around, or underneath the nail. The toenail itself cannot be affected as it is not part of the skin.
How Common Is Toenail Melanoma?
Toenail melanoma is more common in those with darker skin. Of all types of melanoma, only 0.7 to 3.5% of all melanomas affect the nails of white-skinned populations, whereas it accounts for up to 75% of melanomas in Asian and darker-skinned populations.
The condition is more common in those who are older. Most malignant toenail melanomas occur in those who are in their 60s and 70s.