A rare type of skin cancer has been linked to allergic reactions to metal implants, researchers said.
Chronic skin rashes
Some patients who have metal devices implanted near the skin may develop chronic skin rashes caused by contact allergies to metals such as nickel, cobalt and chromium. These rashes may lead to an unusual and aggressive form of skin cancer, the researchers said.
The study's authors described the case of a woman who had a metal rod implanted to repair a broken ankle, and later developed a skin rash near the site of the implant. Doctors determined that the patient was allergic to nickel in the implant and removed the metal rod.
However, the woman's skin rash persisted. A few years later, a rare form of skin cancer called Marjolin's ulcer developed at the woman's rash site. Doctors removed the cancer.
In experiments with mice, the researchers showed that chronic skin inflammation caused by continuous skin contact with allergens can lead to tumour development, according to the study published online in the Journal of Clinical Investigation.
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Patients who have metal devices implanted near the skin may need to be monitored for this type of inflammation, said the researchers at Washington University School of Medicine and Barnes-Jewish Hospital in St. Louis.
They added that their findings also raise the question of whether patients should be tested for metal allergies before receiving metal implants.
Nickel and poison ivy
"A contact allergy is a different kind of reaction from allergies to pollen, pet dander or food," study senior author Dr. Wayne Yokoyama, a professor of medicine, said in a Washington University news release. "A contact allergy usually develops when an allergen touches the skin or is close to it. Skin rash in response to nickel and poison ivy are two common examples of contact allergies."
In this woman's case, some nickel had likely seeped from the implant into her tissue and was still present in her skin even after the implant was removed, he explained.
Study leader Dr. Shadmehr Demehri said allergen-free versions of some implants are available. "These versions may cost more or be less durable, but for some patients with sensitivity to metals, they may be the best option," Demehri, a dermatologist, said in the news release.
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