What Is Merkel Cell Carcinoma?

Merkel cell carcinoma (MCC), also known as neuroendocrine carcinoma of the skin, is a rare and aggressive type of skin cancer. MCC usually appears as bluish-red or flesh-colored nodules on the skin and is usually located on the head, neck, or face. Merkel cell carcinoma affects about 3,000 Americans each year and tends to develop in older people (aged 70+). Additionally, people who have weakened immune systems or long-term UV exposure are also at a greater risk of developing MCC skin cancer. Merkel cell carcinoma spreads rapidly and treatment is contingent upon whether the cancer has spread to other areas of the body. Merkel cell carcinoma can be life-threatening and often recurs after having it removed.

What Are Merkel Cells?

Merkel cells are found in the outer layer of the skin and function mostly as touch receptors. These cells relay touch-related information to the brain. Their highest density is found in the fingertips and lips. They are also referred to as neuroendocrine cells because they produce certain hormones.

Alternative Names for Merkel Cell Carcinoma

Merkel cell carcinoma can be referred to by other names. Other names include:

• MCC
• Merkel cell cancer
• Neuroendocrine carcinoma of the skin
• Trabecular cancer

Signs and Symptoms of Merkel Cell Carcinoma

There are several signs and symptoms that occur with MCC.

Merkel cell carcinoma symptoms include:

• Fast-growing bluish-red, purple, or flesh-colored painless nodules on the skin
• Nodules typically appear on the head, neck, or face, but can develop on other areas of the body, even areas not exposed to sunlight
• A firm and painless lump or nodule
• The nodule may have a shiny appearance
• The nodule might be firm, itchy, or sore and tender

Consult with your healthcare provider if you notice a mole, freckle, or bump that has changed in size, shape, or color. Additionally, if you notice these areas bleeding easily after washing your skin or shaving, contact your healthcare provider immediately.

How to Know if a Nodule Could Be Merkel Cell Carcinoma

There are several signs that may indicate Merkel cell carcinoma. The most noticeable and common sign is the appearance of a nodule or bump that is fast-growing. Nodules tend to appear on the face, neck, arms, or eyelids, or places where there has been UV exposure.

In younger people, these shiny or pearly nodules or lumps may appear on the torso. People with darker skin may be more prone to getting these nodules on their legs. Nodules may also break open into a wound or sore.

Nodule characteristics include:

• Approximately the size of a dime and fast-growing
• Raised up or dome shaped
• Firm
• Itchy
• Tender or sore
• Flesh colored, red, purple, or bluish red
• Similar to a pimple or insect bite

Stages of Merkel Cell Carcinoma

There are five different stages of Merkel cell carcinoma (0–4). Stages help doctors determine how progressed your cancer is. The higher the number, the more severe the progression or spread of the cancer is. Staging also helps doctors determine treatment options. Stages include:

• Stage 0: The cancer is only in the outer layer of the skin (the epidermis) and has not spread to lymph nodes.
• Stage I: The cancer is less than 2cm across and has not spread to the lymph nodes.
• Stage II: The cancer is more than 2cm across and has not spread to the lymph nodes.
• Stage III: The cancer has spread to the lymph nodes and nearby tissue.
• Stage IV: The cancer has progressed to lymph nodes, nearby tissue, and has spread to more distant areas, such as the lungs, bones, or brain.

The cause of Merkel cell carcinoma is unknown. The Merkel cells live deep in the epidermis, the outermost layer of the skin. Merkel cells are connected to the nerve endings that are responsible for the sense of touch. MCC develops when something goes wrong in the cells, causing the cells to grow uncontrollably.

A recent discovery has determined that most cases (8 out 10) of Merkel cell carcinoma are associated with a common childhood virus called Merkel cell polyomavirus (MCP). However, considering how common MCP is, it is believed that there must be several other contributing factors in developing MCC.

What are the Risk Factors for Merkel Cell Carcinoma?

There are several risk factors for developing Merkel carcinoma cancer. Primary risk factors include both genetic and environmental factors.

Risk factors include:

• Excessive exposure to natural or artificial UV light, that can come from the sun or a tanning bed
• Having a compromised or weakened immune system (i.e., people with chronic lymphocytic leukemia, HIV, or those taking immunosuppressant medications)
• Having Merkel cell polyomavirus
• Older age (more common in people over 50)
• Being male
• History of other skin cancers (basal cell carcinoma, melanoma, or squamous cell carcinoma)
• Receiving phototherapy (light therapy) to help treat psoriasis or other skin conditions
• Having fair skin or a lighter complexion

How Is Merkel Cell Carcinoma diagnosed?

Diagnosis of Merkel cell carcinoma  is typically made by a dermatologist or skin cancer specialist after performing a physical examination, gathering a thorough medical history, and looking at results from any imaging tests or biopsies that were performed.

Physical Examination and Medical History

During the initial evaluation for Merkel cell carcinoma, your doctor will conduct a thorough physical examination and review your medical history. They will conduct a full-body skin examination, looking for any suspicious or abnormal growths, as well as checking for any swollen lymph nodes.

Biopsy and Histopathological Examination

If a suspicious or abnormal lump or growth is found, your doctor will perform a biopsy and send a sample of that tissue to a lab for further assessment. Depending on the results of the biopsy, your doctor may order further testing to assess whether the cancer has spread elsewhere in the body.

Imaging Tests for Staging and Metastasis Detection

If Merkel cell carcinoma is detected, your doctor will order imaging tests to assess whether the cancer has spread elsewhere in the body. Early detection of Merkel cell carcinoma is important in preventing it from spreading. Specific imaging tests include:

• MRI
• CT scans
• PET scans

Additionally, if your doctor suspects that the cancer has spread to the lymph nodes, they may perform a sentinel node biopsy, which is when tissue from the nearby lymph node is collected and sent to the lab to see if the cancer has spread to the lymph nodes.

What Treatment Options are Available for MCC Skin Cancer?

There are several options for treating Merkel cell carcinoma. Treatment options will depend on what stage the cancer is in, and where it has spread in the body.

Specific treatment options include:

• Surgical removal of the tumor.
  • Wide excision. Doctors will perform this surgery by cutting out the tumor and about a 1–2-centimeter border of healthy tissue around the tumor.
  • Mohs surgery. This surgery consists of removing one area and layer of skin at a time, until there are no more detected cancer cells in the skin. Due to MCC’s recurring nature, radiation therapy is often recommended after Mohs surgery.
• Radiation therapy. Definitive radiation therapy, which uses targeted X-rays to destroy or shrink cancer cells, may be recommended as the main treatment option, especially when excision surgery would risk damaging other essential structures in the body. It may also be recommended after surgery since there tends to be recurrence with Merkel cell carcinoma.
• Chemotherapy. Although not as common, some cases of Merkel cell carcinoma will be treated with medications that help destroy the cancer cells.
• Immunotherapy. When the cancer has metastasized and spread to other areas of the body, immunotherapy is often recommended. Immunotherapy drugs, known as monoclonal antibodies, help the immune system fight off the cancer cells.

Complications with MCC

Merkel cell carcinoma is a rare and aggressive cancer that has a lower survival rate. This type of cancer is considered aggressive because of how quickly it spreads. Complications of Merkel cell carcinoma result from how quickly it spreads or metastasizes to other areas of the body, such as the lymph nodes, lungs, and brain. How quickly it spreads makes it challenging to treat.

Can you Prevent Merkel Cell Carcinoma? 

There is no guaranteed way of preventing the development of Merkel cell carcinoma. However, there are things you can do to reduce your risk of developing MCC.

Prevention measures include:

• Limiting your exposure to UV light, such as avoiding tanning beds, wearing sunscreen, or staying out of the sun when the UV light is highest.
• If you are at a greater risk of developing Merkel cell carcinoma, it is important to consistently check your skin and look for any suspicious or abnormal lumps, bumps, or growths (moles or freckles that have changed in size, shape, color, or bleed easily).

Early detection is the key to prevention and best treatment outcomes. If you notice any changes or suspicious lumps, bumps, or growths on your skin, it is important to reach out to your healthcare provider.

Learn More about Merkel Cell Carcinoma

It is important to understand the signs and symptoms of Merkel cell carcinoma. Early detection is critical to better treatment outcomes and lowers the risk of complications, so regularly checking your skin for suspicious or abnormal changes is important. Reach out to your healthcare provider immediately if you notice any signs or symptoms of Merkel cell carcinoma.

FAQ

What Is the Life Expectancy of Someone with Merkel Cell Carcinoma?

Life expectancy of someone with Merkel cell carcinoma depends on the severity of the cancer and how much it has spread. Although it is considered a dangerous and aggressive cancer, if it is treated before it has spread, there is a 75% survival rate of 5 years or more.

What Are the Early Signs of Merkel Cell Carcinoma?

Early warning signs of Merkel cell carcinoma include a new appearance of a nodule that is fast-growing. The nodule is described as:

• Shiny or pearly nodule or lesion
• Dime-sized diameter
• Flesh colored, red, purple, or bluish red
• Usually appears on sun-exposed areas, such as the head, neck, and eyelids

Is Merkel Cell Carcinoma Curable?

Merkel cell carcinoma is often curable if detected and treated in the early stages. It is possible that the cancer can come back even after successful treatment.

How Quickly Does Merkel Cell Cancer Spread?

Merkel cell cancer is an aggressive and fast-growing cancer. It usually spreads to nearby lymph nodes first and can also spread to the liver, lungs, bones, or brain.