Subungual melanoma is a form of skin cancer that develops in the tissues beneath a fingernail or toenail, accounting for a small percentage of all melanoma cases. This cancer originates from melanocytes, the cells responsible for producing melanin, the pigment that colors our skin, hair, and eyes. Because of its location, it can be mistaken for other common nail conditions, which can lead to a delay in seeking medical evaluation.
Identifying the Signs of Subungual Melanoma
A primary indicator of subungual melanoma is a brown or black streak that runs the length of the nail. This band of color may be wider than three millimeters and have blurry or irregular borders. Unlike a bruise from an injury that grows out with the nail, a melanoma-related streak remains in place, though it might change in size or appearance over time.
The “ABCDEF” mnemonic is a helpful tool for remembering the signs of subungual melanoma.
- A stands for Age, as it most often affects individuals in their 50s to 70s, and for African American, Asian, and Native American heritage.
- B refers to a brown-black Band of color wider than 3mm or with irregular borders.
- C denotes a Change, such as a rapid increase in the streak’s size.
- D is for the Digit most commonly involved, which includes the thumb, big toe, and index finger.
- E signifies an Extension of pigment into the surrounding skin of the nail fold, known as Hutchinson’s sign.
- F points to a Family or personal history of melanoma, which can elevate risk.
Other symptoms might include spontaneous bleeding, a nodule under the nail, thinning or cracking of the nail plate, or the nail separating from the skin.
Risk Factors and Causes
The specific causes of subungual melanoma are not fully understood and, unlike many other skin cancers, it is not strongly connected to sun exposure. This form of melanoma disproportionately affects people with darker skin tones and is the most common type of melanoma diagnosed in these populations. There is also some association between trauma to the nail and its development, but a direct causal relationship has not been established.
The Diagnostic Process
If a suspicious mark appears under a nail, consulting a dermatologist is the first step. The physician will conduct a physical examination and ask about when the changes began and any relevant medical history. A dermatoscope, a handheld magnifying lens, is often used during this assessment to get a more detailed view of the lesion and surrounding tissue.
While a visual examination is informative, a biopsy is the only way to confirm a diagnosis of subungual melanoma. This procedure involves removing a small tissue sample from the nail matrix, the area at the base of the nail responsible for its growth. The sample is sent to a laboratory where a pathologist examines it under a microscope to determine if cancerous cells are present and to analyze the cancer’s characteristics.
Treatment Approaches
The primary treatment for a confirmed subungual melanoma is surgery to remove the cancerous cells. The goal is the complete removal of the tumor to prevent it from recurring or spreading. The specific type of surgery depends on the size, depth, and location of the tumor.
For early-stage melanomas, a wide local excision may be performed, which involves removing the tumor along with a margin of healthy tissue. In more advanced cases where the cancer has grown deeper into the tissue or bone, amputation of the end of the affected finger or toe might be necessary. If the melanoma has spread to other parts of the body (metastasized), an oncologist may recommend additional treatments such as immunotherapy or targeted therapy.