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Merkel Cell Carcinoma: Causes, Symptoms, and Treatments

Merkel cell tumors are a rare, aggressive type of skin cancer. They mostly occur in adults older than 60 and people who have weaker immune systems.

The first Merkel cell carcinoma symptom is a painless red, purple, or pink bump on the skin. The cancer is often fast-growing, so early treatment for Merkel cell carcinoma is key.

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What Is A Merkel Cell Tumor?

Doctors define Merkel cell tumors as a type of skin cancer. It starts in the Merkel cells, found in the top layer of the skin.

The cancer cells can spread to other parts of the body through the blood or lymphatic fluid.

Because it can show up in the brain, bones, liver, or other organs, Merkel cell carcinoma symptoms can be severe. The cancer can be fatal.

What causes Merkel cell tumors?

Merkel cell tumors happen when the Merkel cell grows out of control.

A healthy immune system can often recognize and destroy these abnormal Merkel cells. Weaker immune systems are less able to hunt down and destroy them.

That's why this cancer is more common in people with weaker immune systems, either from a disease or age.

Some scientists think that a virus called Merkel cell polyomavirus (MCPyV) can lead to Merkel cell cancer. It may cause the tumor or increase the risk of getting it.

Most people get MCPyV at some point. It usually causes no symptoms. Only a small number of people who get the virus get cancer.

What are Merkel cell tumor risk factors and complications?

Merkel cell tumors risk factors

Merkel cell carcinoma (MCC) is more likely in people who:

  • Are 65 or above, though the cancer can occur earlier.
  • Are male, as men are almost two times more likely to get MCC than women.
  • Have fair skin, with 90% of cases occurring in Caucasian people.
  • Have a health problem that weakens the immune system, like HIV/AIDS or chronic lymphocytic leukemia.
  • Have a history of sun exposure (sun tanning, not using sunscreen).
  • Take medicines that weaken their immune system.

Complications of Merkel cell tumors

Merkel cell carcinoma can spread to other tissues and organs in the body. For this reason, it can cause widespread complications, from breathing problems to liver failure.

Merkel cell cancer can be deadly, mainly if it spreads elsewhere in the body.

Why choose UPMC for Merkel cell cancer care?

At UPMC, we know how vital it is to diagnose MCC quickly. We fast-track testing and treatments, as we can offer all advanced imaging and biopsy tests on-site.

Our cancer doctors work closely with you to explain your MCC treatment options and potential side effects.

We offer the latest immunotherapy treatments and take part in clinical trial research. This way, we can offer promising treatments not yet widely available.

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Merkel Cell Cancer (MCC) Symptoms and Diagnosis

What are the signs and symptoms of Merkel cell tumors?

MCC can look like a sore, cyst, or insect bite. Rather than go away, it grows bigger over weeks or months. The bump is often red but can look more pink or purplish and is usually round and shiny.

Most Merkel cell tumors don't cause pain, but the bump can be tender in rare cases. It may also be itchy. They're often found on sun-exposed skin, especially the head, neck, and arms.

But MCC can occur anywhere, even in the skin not exposed to the sun, like in the groin.

Merkel cell cancer often spreads first to the lymph nodes, found in the armpits, neck, belly, groin, and arms. So another Merkel cell cancer symptom is lumps under the skin around a lymph node near the cancer.

How do you diagnose Merkel cell tumors?

If you have a red bump or sore that doesn't go away or grows quickly, see your doctor right away.

They will:

  • Ask about any medications or other health problems you have.
  • Check your skin.
  • Feel your lymph nodes.
To confirm an MCC diagnosis or see if it has spread, they'll order biopsies and imaging tests.

Skin biopsy to diagnose Merkel cell tumors

The doctor takes a small sample of the bump using a needle and sends it to a lab.

Then a lab tech views the sample under a microscope to see if it's cancer.

Lymph node testing

If the skin biopsy is positive for MCC, doctors will check if it has spread to your lymph nodes.

They'll remove one or more lymph nodes and test them for cancerous Merkel cells.

Imaging tests to see if Merkel cell cancer has spread

To see if MCC has spread to other organs in the body, your doctor may order one of the following:

  • A PT scan. You'll receive a shot of a radioactive dye into the blood that fast-growing cancer cells absorb. A CT or MRI scan detects where the dye concentrates in the body.
  • An MRI scan. Looks for unusual masses in the abdomen or chest.
  • A CT scan. To see if the cancer has spread to the lymph nodes in the head and neck, lungs, or other areas.
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What Are the Treatment Options for Merkel Cell Tumors?

The treatment for Merkel cell carcinoma depends on the tumor size and if it has spread.

Surgery to remove Merkel cell tumors

A surgeon will remove the cancer and an area of skin around it that could have cancer cells. They may also remove some or all of the nearby lymph nodes if it's suspected or confirmed they have cancer.

This will happen under anesthesia so that you won't feel any pain.

Radiation to treat MCC

Doctors use radiation therapy to:

  • Kill cancer cells that might remain in the body after surgery.
  • Destroy cancer cells in lymph nodes instead of or in addition to removing them.
  • Shrink a tumor elsewhere in the body if the cancer has spread.

Chemotherapy to treat Merkle cell skin cancer

Chemo drugs for MCC may be in pill form or given via an IV line or shot.

They kill fast-growing cancer cells in the body. But they have many side effects, as they can also hurt healthy cells, like hair cells.

Immunotherapy for MCC


  • Trains your body's immune system to fight cancer.
  • Targets specific proteins of the immune system. By blocking these proteins, the immune cells can better 'find' the cancer cells and destroy them.
  • Can also prolong life for people with advanced MCC.

Merkel cell tumor prognosis and survival

The survival rate for Merkel cell tumors depends on whether the cancer has spread. Treatments cure cancer in some people but may only delay death or reduce MCC symptoms for others.

If the cancer is only in the skin, over half of people with MCC should live five years or more. If it has spread to other organs, death is likely within five years.

Newer treatments are pushing survival rates upwards, allowing people with MCC to live longer.

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