While melanoma is a type of skin cancer, rarely it can also develop beneath the surface of the nail. Called subungual (under the nail) melanoma, it appears as a brown or black streak. Often people delay seeing a doctor because they mistake the discolouration for a bruise, assuming they must have stubbed their toe or hit a finger.

Subungual melanoma often occurs in non-Caucasians. Only about two 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 starts to increase after age 50.

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 any potential signs of subungal melanoma.

Seven signs of nail (subungual) melanoma
  • 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 nail
  • Nail separating from nail bed
  • Darkening skin next to nail (advanced stage)
  • Deformed and damaged nail (advanced stage)