What is Merkel cell cancer?

Merkel cell cancer (MCC) is a rare type of skin cancer that grows quickly. It starts in the Merkel cells. It’s named for the healthcare provider who first described these cells.

Merkel cells are found in the outer layer of the skin. They’re very close to nerve endings. They help the skin sense light touch. 

Merkel cells are a type of neuroendocrine cell. This means they can make certain hormones, too. This cancer is also known as neuroendocrine carcinoma of the skin.

MCC can be dangerous because it tends to grow and spread quickly. It can be hard to treat if it spreads beyond the skin.

What causes Merkel cell cancer?

Experts aren’t exactly sure what causes Merkel cell cancer. But it occurs when Merkel cells in the body change and grow out of control. These abnormal cells may grow to form a lump or mass called a tumor. If the tumor is cancerous, it can grow into (invade) nearby areas. It can even spread to other parts of the body (metastasis), such as lungs, brain, and bones.

Who is at risk for Merkel cell cancer?

A risk factor is anything that may increase your chance of having a disease. The exact cause of someone’s cancer may not be known. But risk factors can make it more likely for a person to have cancer. Some risk factors may not be in your control. But others may be things you can change.

The risk factors for Merkel cell cancer are:

• Being exposed to a lot of ultraviolet (UV) rays from the sun or other sources, such as tanning beds or PUVA treatments used for psoriasis

• Not protecting your skin from the sun

• Having light-colored skin

• Being over age 50

• Being male

• Having a weakened immune system, such as from some types of blood cancer, HIV, or caused by medicines used with an organ transplant

• Arsenic exposure

• Infrared light exposure, such as lasers or heat lamps

Researchers have found that Merkel cell cancer almost always shows infection with a virus known as Merkel cell polyomavirus (MCV). Healthcare providers don’t know much about MCV yet, or how it might be linked to cancer. Most people are infected with this virus at some point. But very few people develop this cancer.

What are the symptoms of Merkel cell cancer?

Most of the time, Merkel cell tumors are found on areas of skin exposed to the sun. These include the face, neck, and arms. But they can start anywhere on the body. They often look like firm, shiny lumps that don’t hurt. The lumps may be red, pink, or blue. The skin on the tumor may open and bleed. They tend to grow very quickly.

How is Merkel cell cancer diagnosed?

The most common way to find Merkel cell cancer (MCC) is when a lump is found and you see a healthcare provider about it. The healthcare provider will look at and feel the lump. They will ask about your health history and do a physical exam of your skin. 

You may be sent to a dermatologist. This is a healthcare provider with special training to treat skin problems. The healthcare provider may use a special light, magnifying lens, or camera to get a very close look at the lump. You will likely need a biopsy. 

A biopsy is the only way to know if a lump or change is cancer. The healthcare provider takes small pieces of tissue from the lump. Your skin will be numbed with medicine before samples can be removed with a needle or scalpel, or during surgery. They are checked with a microscope by an experienced pathologist to look for cancer cells. 

It can be hard to diagnose MCC. It can look like many other types of cancer. Special lab tests can be used on the biopsy sample to find out what’s caused the skin change.

After a diagnosis of MCC, you’ll likely need more tests, such as a CT scan or MRI. This may include taking a biopsy of one or more lymph nodes. These test results help your healthcare providers learn more about the cancer. They can help determine the stage of cancer. The stage is how much and how far the cancer has spread (metastasized) in your body. It’s one of the most important things to know when deciding how to treat MCC.  

Once your cancer is staged, your healthcare provider will talk with you about what the stage means for your treatment. Ask your healthcare provider to explain the stage of your cancer to you in a way you can understand.

How is Merkel cell cancer treated? 

Your treatment choices depend on the number of Merkel cell cancer tumors, test results, and the stage of the cancer. The goal of treatment may be to cure you, control the cancer, or to help ease problems caused by cancer. Talk with your healthcare team about your treatment choices, the goals of treatment, and what the risks and side effects may be. 

Types of treatment for cancer are either local or systemic. Local treatments remove, destroy, or control cancer cells in one area. Surgery and radiation are local treatments. Systemic treatment is used to destroy or control cancer cells that may have traveled around your body. When taken by pill or injection, chemotherapy and targeted therapy are systemic treatments. You may have just one type of treatment or a combination of treatments.

Sometimes more than one type of treatment is used. Treatment may include:

• Surgery. Removing the tumor is the main treatment. This may include removing an edge of healthy tissue around the tumor. Merkel cell cancer grows fast and often spreads. So your healthcare provider may also remove a sentinel lymph node or more nearby lymph nodes and check them for cancer. A sentinel lymph node is the node closest to where the tumor first started.

• Radiation therapy. This uses X-rays or other types of radiation to kill cancer cells and shrink tumors. This may be used after surgery. It may be the main treatment if surgery is not a choice.

• Chemotherapy. This uses medicines that kill cancer cells. It goes throughout the body and may be needed when the cancer has spread to other parts of the body.

• Immunotherapy. These medicines work with your immune system to kill cancer cells. It’s helpful when the cancer has spread beyond your skin. One type is called immune checkpoint inhibitor therapy.

Talk with your healthcare providers about your treatment choices. Make a list of questions. Think about the benefits and possible side effects of each choice. Some treatments may affect your ability to have children in the future. Talk about your concerns with your healthcare provider before making a decision.

How can I help prevent Merkel cell cancer?

Limit your exposure to UV light and don't use tanning beds or sunlamps. Keep your immune system strong by staying away from HIV exposure. Early diagnosis and treatment of Merkel cell cancer is important to prevent it 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 grow larger, bleed, crust, or itch. Your healthcare provider may recommend you do a skin self-exam once a month or more. See your healthcare provider if you have any new or changing marks on your skin.

Coping with Merkel cell cancer

Many people feel worried, depressed, and stressed when dealing with cancer. Getting treatment for cancer can be tough on your mind and body. Keep talking with your healthcare team about any problems or concerns you have. Work together to ease the effect of cancer and its symptoms on your daily life.

To help ease your stress:

• Talk with your family or friends.

• Ask your healthcare team or social worker for help.

• Speak with a counselor.

• Talk with a spiritual advisor, such as a minister or rabbi.

• Ask your healthcare team about medicines for depression or anxiety.

• Keep socially active.

• Join a cancer support group in person or online.

Cancer treatment is also hard on the body. To help yourself stay healthier, try to:

• Eat a healthy diet, with a focus on high-protein foods.

• Drink plenty of water, fruit juices, and other liquids.

• Keep physically active.

• Rest as much as needed.

• Talk with your healthcare team about ways to manage treatment side effects.

• Take your medicines as directed by your team.

When should I call my healthcare provider?

Call your healthcare provider right away if you have any these: 

• New symptoms or symptoms that get worse

• Signs of an infection, such as a fever

• Side effects of treatment that affect your daily function or don’t get better with treatment

Ask your healthcare provider what signs to watch for and when to call. Know how to get help after office hours and on weekends and holidays.

Key points about Merkel cell cancer

• Merkel cell cancer is a rare type of skin cancer. It forms in the Merkel cells. These cells are found in the outer layer of the skin.

• Merkel cells are very close to nerve endings. They help the skin sense light touch.

• Being exposed to a lot of UV light can raise your risk for this cancer.

• Merkel cell cancer often looks like firm, shiny lumps on your skin that don’t hurt. They may be red, pink, or blue.

• This cancer grows and spreads quickly.

• Treatment includes surgery, radiation, chemotherapy, and immunotherapy. One type of treatment or a combination of treatments may be used.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

• Know the reason for your visit and what you want to happen.

• Before your visit, write down questions you want answered.

• Bring someone with you to help you ask questions and remember what your provider tells you.

• At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.

• Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.

• Ask if your condition can be treated in other ways.

• Know why a test or procedure is recommended and what the results could mean.

• Know what to expect if you do not take the medicine or have the test or procedure.

• If you have a follow-up appointment, write down the date, time, and purpose for that visit.

• Know how you can contact your healthcare provider if you have questions, especially after office hours or on weekends.