What is a Merkel cell?
- Merkel cells are a type of neuroendocrine cell. This means they have features of both nerve cells and hormone-making cells.
- Merkel cells are mostly found in the outermost layer of the skin and in hair follicles. Merkel cells relay the sensation of touch from the skin cells that provide barrier function – keratinocytes - to nerve fibers located in the skin.
What is Merkel cell carcinoma?
Merkel cell carcinoma is a rare type of skin cancer. It is also known as primary neuroendocrine carcinoma of the skin, trabecular carcinoma of the skin, primary small cell carcinoma of the skin and cutaneous apudoma. Merkel cell carcinoma tends to grow quickly. Treatment options depend on if it has spread beyond the skin.
What does Merkel cell carcinoma look like? What are the symptoms?
Merkel cell carcinoma is different from other skin cancers in that it does not have a common identifiable trait across all cases.
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.
- usually appear as firm, shiny skin lumps that don't hurt. The lumps may be red, pink, purple, or blue.
- tend to grow very quickly.
Between 10– 20% of cases (between 10 and 20 people out of every 100) present without skin involvement and are found as a swelling of a lymph node.
How is Merkel cell carcinoma diagnosed?
- Merkel cell carcinoma is diagnosed with a biopsy. A biopsy is a sample of tissue that is removed from a patient. The sample is taken with a needle, scalpel, or during surgery. Next, it is tested in a lab to see if cancer cells are present.
- Diagnosing Merkel cell carcinoma can be difficult because it can look like many other types of cancer.
When should I see a doctor?
- You should see your doctor if you have any new or changing marks on your skin. 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 grow larger, bleed, crust, or itch.
- Early diagnosis and treatment is important to prevent the cancer from spreading. Your healthcare provider may recommend you do a skin self-exam once a month or more.
What are the risk factors for Merkel cell carcinoma?
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 UV (ultraviolet) 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 are at higher risk for this cancer. This can include people who have had an organ transplant or are receiving chronic immunosuppressive treatment for autoimmune diseases or 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.
Researchers have found that most Merkel cell carcinoma tumors are infected with a virus known as Merkel cell polyomavirus (MCV). Most people are infected with this virus at some point but very few people develop this cancer.
What causes Merkel cell carcinoma?
MCC is believed to be caused by either damage from ultraviolet radiation (UVR) from the sun or a common virus (Merkel cell polyoma virus) that almost all adults have been exposed to.
Is Merkel cell carcinoma contagious?
Even though most Merkel cell carcinoma tumors are caused by the Merkel cell polyoma virus, there is no evidence that this cancer is contagious. The Merkel cell polyoma virus is pervasive and the vast majority of people have been exposed to it by the time they are adults.
How is Merkel cell carcinoma treated?
Treatment options can include surgery, radiation or medical therapy. Because treatment options remain limited for Merkel cell carcinoma, when available and appropriate, clinical trials are often recommended.
Following staging, treatment is often done with more than 1 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 provider 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 it may be the main treatment if surgery is not an option.
- Medical Therapy. This treatment is done with medicines. It helps destroy cancer cells in cases where the cancer has spread to other parts of the body. An approved medication for Merkel cell carcinoma works by stimulating the body’s immune system.