Nail Streaks: A Concern for Melanoma?

Melanoma is a type of cancer that may affect any part of the body with melanocytes, the cells that produce melanin. Melanoma can occur in the hands and feet, including the nails of both extremities. It occurs in all ethnic groups and skin types; however, unlike other skin cancers that are associated with sunlight, nail melanoma occurs regardless of sunlight exposure.^[1]

How do you know if you have nail melanoma? The ABCDE mnemonic can serve as a guide to alert you to see a dermatologist when malignancy may be suspected. When it comes to nail melanomas, the ABCDE mnemonic was altered and the ABCDEF mnemonic created to guide both clinicians and patients to identify key features that may raise suspicion for cancer in the nail. Here’s when you should worry about melanoma:

Age: When You’re in the Age Range

Nail melanoma can affect anyone from the ages of 20-90 years old but it more commonly peaks in the 50-70’s age group.

Band: When There’s a Nail Band

The nail band present in melanoma happens due to an increased amount of pigmentation in the nail matrix (“root” of the nail), not associated with an increase in the number of melanocytes. It usually presents as a brown to black band or streak on the nail, also known as melanonychia.^[2] Several studies have shown that there are other causes for a nail streak. Some examples are drugs, fungal infections, nail bleeding, and other non-malignant tumors of the nail.^[3] Unfortunately, nail melanoma is commonly misdiagnosed and treatment is often delayed.^[1]

Change: When It Changes in Size and Color

Having an initial picture of the band may be helpful in order to note if any changes in growth or darkening of the lesion are happening. An increase in the size of the band over a period of time is valuable information for a proper diagnosis.

As previously mentioned, clinicians may often misdiagnose the lesion and perhaps treat for some other cause. If treatment is in place and no changes are noticed, then suspicion of some other condition should be considered, including an underlying malignancy.

Digits: When the Toes or Thumbs Are Involved

Digit involvement is important, as the big toe and the thumb are most commonly affected. This is in contrast to other patterns of melanonychia, such as in patients with darker skin tones, which more commonly affect the thumb and index finger.^[2] Another differentiation pattern of digit involvement is seen in trauma-related melanonychia when the 4^th and 5^th toenail are bilaterally involved due to incorrect shoe size.^[2]

Extension: When It Extends

Nail bands that extend greater than 2.5mm-3mm are highly suspicious of nail melanoma as they may spread to the surrounding skin.^[1] Dermatologists can easily assess extension by using a dermascope and seeing if the pigment is the same in the areas of involvement. If so, there is a greater likelihood of melanoma.

Family History: When There Is Family History

Lastly, physicians should be able to assess clinical and familial history. Studies have shown that melanoma is associated with a family history of melanoma and/or dysplastic nevus syndrome,^[4] a skin condition where many moles are present.

Noting all of these changes can be crucial for a proper diagnosis and further, a successful treatment. Melanoma of the nail carries a poorer prognosis compared to skin melanomas and it is often due to a delay in diagnosis, misdiagnosis, and late treatment. It is important for patients and clinicians alike to be aware of changes in the nail unit and the duration of them, as nail melanoma is a time-sensitive issue that can be treated effectively if diagnosed early.