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Discolored Nails Extra – What is Melanonychia and What Causes It?

Melanonychia is brown or black discoloration of a nail.

Longitudianl melanoma
Nail Longitudianl melanoma

Melanonychia can present in individuals of all ages, including children, and affects both sexes equally. It can appear on fingernails and toenails. It is more prevalent in people with skin of color.

  • Nearly all Afro-Caribbean people will develop black-brown pigmentation of the nails by the age of 50
  • Melanonychia affects up to 20% of Japanese people
  • White-skinned people are less commonly affected

What Causes Melanonychia?

The nail plate is a hard, translucent structure made of keratin. It is not normally pigmented.
Melanocytes typically lie dormant in the proximal nail matrix where the nail originates.
The nail plate is usually semitransparent because of a lack of melanin, however, under some circumstances, melanin can cause nail discoloration, leading to melanonychia.

Longitudinal Melanonychia

Melanin is deposited into the growing nail when melanocytes are activated, resulting in a pigmented band — this is longitudinal melanonychia.

The deposition of melanin in the nail plate can result from 2 processes:

  • Melanocytic hyperplasia – Melanocytic hyperplasia refers to an increased number of melanocytes within the nail matrix.
  • Melanocytic activation – Melanocytic activation is an increase in the production and deposition of melanin into the nail plate cells, without an increase in the number of melanocytes.

What is Melanoma of the Nail Unit?

melanonychia in single nail

75%-90% of Melanoma of the nail unit most commonly affects the thumbs, index fingers and big toes. 

Melanomas can originate:


How Can Nail Technicians Help?

As a nail technician, your knowledge should help you spot any changes in the nail plate or skin surrounding the nail plate early – consumers doing their own nails need to be made aware of this fact. To the untrained eye normal longitudinal pigment stripes might be mistaken for a melanoma. If you or your client are worried about any changes in color to the nail plate or surrounding skin you need to contact a medical doctor.

Never tell a client that they have cancer, you don’t know that to be a fact.

You can suggest that letting a medical professional have a look is a wise thing to do, just in case.

How to recover the nail plate:

Do not apply artificial nail products until the cause of the pigment stripes is known. Nail Unit maintenance is always important. If the Medical Professional is happy that it’s just a pigment stripe and as long as the nail plate itself is intact then feel free to make your client happy with a gel polish enhancement.

Nail Enhancements:

If the pigmentation is caused by overactive melanocytes and the nail plate is intact there is no contra indication for nail enhancements or nail coatings.

How to prevent Melanonychia:

You can’t.

DODon’tNail ProductRefer to MD
Keep a record, measurements & photosCover with nail products without knowing what the cause isIf the lines change or reach a size <3mm
Keep clean, wash regularly with soap & WaterDisguise with artificial nail productsOil & Lotion
If you or your client are worried
Mention or Diagnose a serious conditionIf the nail becomes infected or changes color

Contra Indication:

If the nail unit is painful or swelling occurs refer to a MD

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