New Cautions for Metal Implant Allergies

A patient who developed a skin rash after having a metal rod implanted to repair her fractured ankle alerted researchers to a skin cancer that is linked to a patient’s allergy to a metal orthopedic implant. Some people are allergic to metals such as nickel, cobalt and chromium—the same metals used to make orthopedic implants stronger and more durable. Research, reported by Michael C. Purdy, senior medical sciences writer at Washington University School of Medicine, suggests that patients with allergies to metals may develop skin rashes from their implants. And these inflammations have the potential to turn into an unusual and aggressive form of skin cancer known as Marjolin’s ulcer.

Researchers at Washington University School of Medicine and Barnes-Jewish Hospital in St. Louis published their findings about metal allergies and implants in the Journal of Clinical Investigation.

Purdy reports that the patient’s diagnosis with Marjolin’s ulcer, an invasive and potentially deadly squamous cell cancer, surprised physicians. To find out if inflammation from the metal rod in her ankle could have caused the cancer they turned to mouse models. “This model supported cancer development so strongly that some mice developed invasive squamous cell skin cancers similar to the patient’s tumor, ” said lead author Shadmehr Demehri, M.D., Ph.D., a dermatologist and postdoctoral fellow.

Purdy quoted Wayne M. Yokoyama, M.D., a Howard Hughes Medical Institute investigator at the School of Medicine, “A contact allergy is a different kind of reaction from allergies to pollen, pet dander or food. 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.”

The investigators demonstrated that contact allergies attract inflammatory cells to the site of the reaction. If the contact continues, other cells arrive at the site forming a mix that can lead to the development of skin tumors. The case raises the question whether allergic reactions to metal implants should be determined in advance by patients planning to have an implant installed. “Allergen-free versions of some implants are available, ” Demehri said to Purdy. “These versions may cost more or be less durable, but for some patients with sensitivity to metals, they may be the best option.”