Doctors thought she had cancer — until they saw her lymph nodes covered in black ink

Old tattoos can still cause new health problems, even if they are 15-years-old.

That’s according to a new report in the journal Annals of Internal Medicine, which details how one Australian woman’s seemingly surefire case of cancer actually turned out to be nothing more than an adverse reaction to black tattoo ink.

The unnamed 30-year-old woman came into the Royal Prince Alfred Hospital with small lumps under her arm that had been there for two weeks, according to the Telegraph.

Doctors then conducted a body scan, according to CNN, only to find more swollen lymph nodes in her chest and at the roots of her lungs.

Dr. Christian Bryant, a hematologist at the hospital and one of the woman’s doctors, was certain she had lymphoma, a form of cancer that results in swollen lymph nodes.

“Ninety-nine times out of 100, (this) will be lymphoma,” he said to CNN.

But Bryant and his colleagues were wrong — the concerned woman didn’t have lymphoma, or any type of cancer at all, for that matter.

Instead, she was just experiencing an adverse reaction to a tattoo inked upon her back nearly two decades earlier.

Doctors made that stunning discovery after they removed a lymph node from the woman’s neck to examine it and found immune cells covered in black pigment from an old tattoo.

Dr. Bill Stebbins, a director of cosmetic dermatology at Vanderbilt University Medical Center, told CNN it’s not yet known why the woman’s body took so long to react to the tattoo.

He added that immune cells ingest tattoo pigment because it is a foreign substance — even though the cells can’t get rid of the ink.

“The pigment is too large for these cells to eat and digest,” Stebbins said. "That's why they're still there many years later.”

While this woman’s case remains a mystery, doctors suggest finding a trustworthy tattooist and telling them of any allergies you have before getting inked up. You’ll also want to make sure that all of the tattooist’s devices are properly cleaned.

But don’t worry, tattoo fanatics: Between 2014 and 2016, the FDA received just 363 reports of adverse reactions to tattoos, according to Refinery29.

Still, that leaves Bryant wondering — how many people have also experienced similar symptoms from a tattoo?

“I think there's absolutely no way to know how common it is,” Bryant said to CNN. “Most people who have tattoos have absolutely no problems.”

This story was originally published October 3, 2017 at 12:03 PM with the headline "Doctors thought she had cancer — until they saw her lymph nodes covered in black ink."