Australia.  Doctors thought 30 year-old woman had lymphoma due to her symptoms, but it was due to her immune system response to a 15-year old tattoo.  After removing her swollen lymph node, they found black tattoo pigment in it.

She had small lumps under her arms for 2 weeks, and a body scan showed even more enlarged lymph nodes in her chest, including near the bottom of her lungs.

“Ninety-nine times out of 100, (this) will be lymphoma,” said Dr. Christian Bryant, a hematologist at the Royal Prince Alfred Hospital in Sydney. Bryant is one of the woman’s doctors.

Many cancers — including lymphomas, which come from immune cells — can cause lymph nodes to swell. Lymph nodes may also enlarge due to infection and inflammation.

In the case of the Australian woman, whose name was not released, her lymph nodes were inflamed because of a reaction to the old tattoo ink, not due to cancer cells. Doctors removed a lymph node from her armpit and found a cluster of immune cells that were loaded with black pigment.

The woman had a 15-year-old tattoo covering her back, and there was a smaller, more recent one on her shoulder.

“The skin has its own immune cells that are always surveilling the skin,” said Dr. Bill Stebbins, director of cosmetic dermatology at Vanderbilt University Medical Center, who was not involved in the report.

Once these immune cells found the tattoo pigment, a foreign substance, they ingested it and traveled from the skin to the lymph nodes over a period of years.

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

...Something set off the immune cells, but her doctors couldn’t pin down what that trigger might be, Bryant said. The patient noted that her tattoos would occasionally itch, but only for a few days each month.

The type of inflammatory response found in her lymph nodes, called a granuloma, was not found in her skin.

via "15-year-old tattoo to blame for woman’s ‘cancer’ scare"

Something to think about before deciding to get a tattoo.  This article says that according to a Pew Research Center report, in the U.S. nearly 40% of millenials, 32% of Generation X, and 15% of baby boomers  have tattoos.