A black area or streak on the big toenail can have multiple causes, and one of them is melanoma.

What are all the things that a black spot or area on the big toenail can possibly mean?

“Fungus, bleeding under the toenail from trauma (talin Noire, runner’s nail), congenital mole, atypical mole, melanoma,” says Dr. David Rahimi, MD, a board-certified dermatologist and cosmetic surgeon.

What are the odds that this sign is melanoma?

Dr. Rahimi says, “Melanoma under the nail is very uncommon.

“I have seen four in 16 years of clinical practice. It is more common in patients with darker skin color: Asian, Hispanics and African Americans.”

Tell-tale features of melanoma?

“If the spot has been there for months, growing in darkness and size, and most importantly:

“Pigmentation in the proximal nail folds–meaning the color is spilling into the skin portion of the nail. This is called the Hutchinson’s sign.”

Hutchinson’s sign

NOTE: Melanoma in the toenail can occur even if the patient’s foot has had very little lifetime exposure to the sun.

Always look at your feet! This includes between the toes and on the soles.

Have a dermatologist inspect your feet once a year.

Dr. Rahimi is the founder of Forever Young, Inc.
Lorra Garrick has been covering medical, fitness and cybersecurity topics for many years, having written thousands of articles for print magazines and websites, including as a ghostwriter. She’s also a former ACE-certified personal trainer.