It was a bruise, a decade-old tan streak on her nail, she thought. It was a rare form of skin cancer.

Tan streak on woman's thumb nail revealed rare form of skin cancer.Doctors advised against biopsying the 25-year-old patient's harmless mole.

Skin cancer is treatable when detected early, so routine exams are critical.

One woman, 25, had a harmless mole under her nail for 10 years before it turned out to be an aggressive skin cancer, TODAY reported.

Sylvia said a tan streak appeared under her nail around 2012, and she assumed it was a sports bruise.

Sylvia told TODAY that a dermatologist said it was most likely a mole in her nail bed, with a 1% chance of cancer.

Sylvia had the mark rechecked in late 2021 after a coworker said it resembled a cancerous condition, but she had to insist on a biopsy after another dermatologist wasn't concerned.

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