Doctors thought her swollen lymph nodes were a sign of lymphoma.

Amanda MacMillan
October 03, 2017

When a 30-year-old woman in Australia visited her doctor about two small but stubborn lumps under her arm, she was told to brace for bad news. A PET scan showed a mass that looked like lymphoma, or cancer of the lymph nodes.

But the woman and her doctors were in for quite a surprise: A biopsy showed that her lymph nodes weren’t swollen because of cancer, but because her immune system was reacting to ink from a tattoo she’d gotten 15 years earlier.

The woman’s doctors, from Royal Prince Alfred Hospital in Sydney, recounted the odd story this week in the Annals of Internal Medicine, warning other physicians that tattoo pigment collected in lymph nodes can mimic lymphoma during physical exams and imaging tests.

Some of the better-known complications of tattoos include pain, infection, and hypersensitivity, the authors write in their case study. But delayed reactions to tattoos have also been reported up to 30 years after being inked, they add, including enlarged lymph nodes. One recent study found that nanoparticles of tattoo pigment (including toxic metals) travel through the body and collect in the lymph nodes, actually turning them different colors.

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Lymph nodes are abundant in the area under the arm, which is one reason why this year’s trendy armpit tattoos may not be such a great idea, some doctors say. In this case, the woman didn’t have a tattoo under her arm—but she did have a large, black one on her back that she’d received 15 year earlier, and a smaller 2-year-old design on her shoulder.

Her doctors didn’t think much of her ink, until they surgically removed an enlarged, inch-long lymph node from under her arm. Where they expected to find cancer, they instead discovered that the gland had been stained black by tattoo pigment. It was also filled with a cluster of immune cells, known as a granuloma, that had likely gathered there to fight off what the body perceived as a foreign threat.

It was then that the doctors connected the enlarged lymph node with the patient’s tattoo. When they asked her about it, she admitted that the 15-year-old body art still became itchy and raised for a few days every month—further evidence that her body was still trying to reject the ink even after all that time.

Luckily, the patient had no further symptoms after the enlarged lymph node was removed. Ten months later, she’d developed no additional lumps.

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The doctors say that immune reactions to tattoos aren’t terribly uncommon, and that tattoo-triggered granulomas have been documented plenty of times in medical research. In some instances, they’ve even been mistaken for skin cancer.

But this case was unusual, and much more difficult to diagnose, because only the lymph nodes were involved—and not the skin itself. “We believe that this case highlights the importance of a careful tattoo history and physical examination,” the doctors wrote.