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. MCC 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. MCC spreads rapidly and treatment is contingent upon whether the cancer has spread to other areas of the body. MCC can be life-threatening and often recurs after having it removed.

Signs and Symptoms

There are several signs and symptoms that occur with MCC.

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.

Causes

The cause of Merkel cell carcinoma is unknown. The Merkel cells live deep in the epidermis, the outer most 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 MCC 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.

Risk Factors

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

Diagnosis

Diagnosis of MCC 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 MCC is detected, your doctor will order imaging tests to assess whether the cancer has spread elsewhere in the body. Early detection of MCC 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.

Treatment

There are several options for treating MCC. 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 MCC.
• Chemotherapy. Although not as common, some cases of MCC 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.

Prevention

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 MCC, 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 MCC.