Common Causes And Risk Factors For Subungual Melanoma

Subungual melanoma is a form of cancer that begins in the cells of the skin lining the underside of an individual's fingernail. Subungual melanoma can go undetected before it spreads to other parts of the body because it occurs in a location not exposed to excessive sunlight and appears similar to normal bruising of the fingernail. This type of cancer usually begins as a dark-colored streak under the toenail or fingernail. The streaks will increase in size and not move up as the nail grows. The affected fingernail or toenail may separate from the nail bed, develop a nodule, bleed, crack, or become distorted. Diagnosis of subungual melanoma is made by eliminating onychomycosis, paronychia, pyogenic granuloma, and squamous cell carcinoma. A biopsy can confirm the diagnosis. More tests will be run to determine if and how much the subungual melanoma has spread.

Sun Exposure

Some cases of subungual melanoma are the result of excessive sun exposure because of the same mechanism that causes other forms of skin cancer. While this is not the cause of most cases of subungual melanoma, it does account for a good portion of them. The sun emits ultraviolet rays that can cause damage to the cells that make up the skin. To protect itself, the body has a substance in the skin cells referred to as melanin, which is what gives the hair and skin on the body its pigment. Freckles and moles on the skin develop when there is an abnormal concentration or deposit of cells with high amounts of melanin in one small area. The cells underneath the nail also contain melanin and are susceptible to damage from the sun. After repairing the cellular DNA damage from repeated sun exposure, the body tends to miss some genetic damage and make mistakes that cause mutations in the affected cells, which can result in their proliferation and malignancy. When this process occurs in the skin underneath a nail, it is referred to as subungual melanoma caused by sun exposure.