Melanoma is a type of skin cancer that can rarely develop beneath the surface of the nail. Called subungual (under the nail) melanoma, it appears as a brown or black streak. People may delay seeing a doctor because they mistake the discoloration for a bruise, assuming they’ve stubbed their toe or hit a finger.

Subungual melanoma often occurs in non-Caucasians. Only about 2 per cent of cases are in white-skinned individuals, whereas about 30 to 40 per cent of cases are in non-whites. However, many dark-skinned people may have streaks in their nails that are not cancer; these do not change or increase in size. Men and women are at equal risk, and the risk increases after age 50.

Most subungual melanomas occur in the thumbnail or big toenail, although it can develop in any nail. Repeated injury to finger- or toenails has been identified as a risk factor for developing subungual melanoma.

Like other forms of melanoma that typically surface on skin, subungual melanoma can spread to other parts of the body, including organs and lymph nodes — and it can be deadly. Always see a dermatologist as soon as possible if you notice potential signs of subungual melanoma.

The outlook for this type of melanoma is poorer than for others because diagnosis is often delayed. The five-year survival rate for subungual melanoma can vary greatly – from 16 to 87 per cent– depending how extensively the cancer has spread.

  • a brown or black streak
  • streaks that increase in size
  • no known injury to the nail
  • a bruise that does not heal or grow out with the nail
  • nail separating from nail bed
  • ulcer, nodule or bleeding developing
  • darkening skin next to nail (advanced stage)
  • deformed and damaged nail (advanced stage)

Treatment involves surgicallyremoving the melanoma, often involving the whole nail. Sometimes the end of the affected finger or toe is also amputated, but doctors try to avoid this. Sentinel node biopsy may also be undertaken to determine whether the melanoma has spread to the lymph nodes.