Merkel cell carcinoma is a rare type of skin cancer. Merkel cells are types of cells in the upper layer of the skin. The cells are very close to nerve endings, and help the skin sense light touch. Merkel cell carcinoma occurs when these cells grow out of control. Merkel cell carcinoma can be dangerous because it tends to grow quickly. It can be hard to treat if it spreads beyond the skin.
Merkel cells are a type of neuroendocrine cell. This means they have features of both nerve cells and hormone-making cells. The cancer is also known as neuroendocrine carcinoma of the skin.
The known risk factors for Merkel cell carcinoma include:
Exposure to UV rays. Like many other types of skin cancer, the risk of Merkel cell carcinoma is higher in people who have been exposed to a lot of ultraviolet (UV) rays from the sun or from other sources like tanning beds. People who are treated for psoriasis with UV rays may also have a higher risk.
Weakened immune system. People with weakened immune systems, such as people who have had an organ transplant, are at increased risk for this cancer.
Light-colored skin. People with lighter skin are at higher risk.
Older age. People older than 50 are more likely to get this cancer.
Being male. Men are more likely to get Merkel cell carcinoma.
Researchers have found that Merkel cell carcinoma almost always shows infection with a virus known as Merkel cell polyomavirus (MCV). It is not known how the virus may contribute of the growth of this cancer. Most people are infected with this virus at some point, and very few people develop this cancer.
Merkel cell carcinoma tumors are most often found on sun-exposed areas of skin, such as the face, neck, and arms. But they can start anywhere on the body. They usually appear as firm, shiny skin lumps that do not hurt. The lumps may be red, pink, or blue. They tend to grow very quickly.
The diagnosis of Merkel cell carcinoma is made with a biopsy. This is a sample of tissue that’s taken to test in a lab. Tumor samples are removed with a needle or scalpel, or during surgery. They are checked with a microscope to see if cancer cells are present. Diagnosis of Merkel cell carcinoma can be difficult. It can look like many other types of cancer.
Early diagnosis and treatment of Merkel cell carcinoma is important to prevent the cancer from spreading. Be aware of any lumps, growths, moles, or other abnormal areas on your skin. Watch for new spots or areas that are changing. This can include skin marks that as grow larger, bleed, crust, or itch. Your health care provider may recommend you do a skin self-exam once a month or more. See your health care provider if you have any new or changing marks on the skin.
Treatment is often done with more than one method. Treatment methods include:
Surgery to remove the tumor. This may include a border of healthy tissue. Since Merkel cell carcinoma grows fast and often spreads (metastasizes), your doctor may also remove nearby lymph nodes.
Radiation therapy. This therapy uses X-rays to kill cancer cells and shrink tumors. This may be used after surgery, or be the main treatment if surgery is not an option.
Chemotherapy. This treatment is done with medicines. It helps destroy cancer cells in cases of more advanced disease.