Merkel cells are found just below your skin’s surface, on the lowest level of your top layer of skin (the epidermis). Connected to nerve endings associated with the sensation of touch, Merkel cells play a key role in helping us identify fine details and textures by touch.
A rare and dangerous form of skin cancer known as Merkel cell carcinoma is thought to originate from Merkel cells when they grow out of control. This disease usually appears as a painless skin nodule (lump) that can be skin-colored, red, or violet, most often developing in areas of skin exposed to the sun, especially the face, head, and neck. But these nodules can develop anywhere on the body, even areas not often exposed to sunlight.
Merkel cell carcinoma tends to grow quickly and spread to other parts of the body, making it a particularly dangerous form of skin cancer. Treatment options usually depend on whether the cancer has spread beyond the skin, but can include surgery (to remove the cancer), radiation therapy, and chemotherapy.
It’s not clear what causes Merkel cell carcinoma, but it most often develops in people age 50 or older and in people with weakened immune systems. Long-term exposure to sunlight is considered a risk factor, so it’s important to always stay safe in the sun to reduce your risk of Merkel cell carcinoma and other types of skin cancer.
To help prevent problems, check your skin regularly. If you notice a mole, freckle, or bump that changes color, size, or shape, talk with your doctor. Most skin nodules don’t become cancer, but catching cancer in its early stages can dramatically improve treatment outcomes.
Dana-Farber’s Center for Cutaneous Oncology offers more information about Merkel cell carcinoma and other types of skin cancer.