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Black or Brown Discoloration in Your Nail: What Does it Mean?

By HERWriter
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Black or Brown Streaks in Fingernails: What Does it Mean?  Via Unsplash

Have you ever noticed a lengthwise black or brown band or streaks in your fingernails? There are several causes, some are more serious than others, but the most important cause could be melanoma of the nail called subungual melanoma.

Nail discoloration that occurs as a vertical line is also called longitudinal melanonychia. It occurs due to an overproduction of melanocytes in that area of the nail. These streaks in fingernails are sometimes caused by “nail moles” and similar to moles elsewhere in the body, may not develop into a more serious problem but still need to be monitored. Nail moles are more common in children.

Nail pigment bands or melanonychia are quite common in people who have dark skin. It is estimated that 70 percent of African Americans over the age of 20 have nail banding and almost all African Americans over the age of 50 have some type of nail pigment discoloration. Only 10-20 percent of those of Japanese decent have melanonychia and it occurs in less than two percent of Caucasians.

Melanonychia that is found to be skin melanoma (subungual melanoma) has the highest morbidity over other sites in the body so any nail discoloration should be evaluated by a dermatologist. The doctor will review symptoms based on an A through F list to rule out whether melanoma is the cause.

● A: Age. Subungual melanoma is more common in those ages 50 to 70.
● B: Brown/black band is wider than three millimeters.
● C: Change has been noted in the look of the pigment band.
● D: Digit involved. The thumb is the most common, then the great toe and last the index finger.
● E: Extension of the discoloration into the cuticle or nail fold (called Hutchinson sign).
● F: Family history of melanoma.

There are numerous other reasons why nail pigment banding occurs: trauma to the nail, medication, systemic diseases, vitamin deficiencies and other skin conditions which may also appear as banding in more than one finger. A doctor should review your entire medical history to determine what the next step is to take.

If nail melanoma is suspected then a biopsy will be performed. If nail melanoma is found, surgery will be performed to remove the entire nail complex and Mohs micrographic surgery, which has an extremely high cure rate, may be performed.

One area women need to be more vigilant than men in monitoring nail health is that women often wear nail polish or acrylic tips covering the nail making it hard to observe any changes. Make sure that in between polishes or nail treatments you consciously take a close look at your finger and toenails to note any discolorations. If you notice a pigment change, don’t delay seeking out medical attention to follow up.


Photo of nail melanoma

Michele is an R.N. freelance writer with a special interest in woman’s healthcare and quality of care issues. Other articles by Michele can be read at www.helium.com/users/487540/show_articles

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EmpowHER Guest

What nutrient deficiencies are associated with the benign brown discoloration/ line?

April 25, 2017 - 9:50am
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We value and respect our HERWriters' experiences, but everyone is different. Many of our writers are speaking from personal experience, and what's worked for them may not work for you. Their articles are not a substitute for medical advice, although we hope you can gain knowledge from their insight.