Merkel Cell Carcinoma

(Neuroendocrine Skin Carcinoma; Trabecular Cell Carcinoma; APUDoma of the Skin)

ByVinod E. Nambudiri, MD, MBA, EdM, Harvard Medical School
Reviewed/Revised Jan 2024
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Merkel cell carcinoma is a rare, rapidly spreading skin cancer that tends to affect older White people.

Merkel cells are normal cells in the epidermis (the outer layer of the skin). These cells mostly function as touch receptors and they produce certain hormones. Merkel cell carcinoma arises from uncontrolled growth of cells in the skin that share some characteristics with normal Merkel cells.

Merkel cell carcinoma is diagnosed at an average age of 75 years. It also affects younger people whose immune system is weakened. Sun exposure increases the risk, as does having another cancer (such as melanoma or chronic lymphocytic leukemia). The Merkel cell polyomavirus may be a contributory factor.

This cancer commonly spreads to the lymph nodes.

Symptoms of Merkel Cell Carcinoma

The cancer is typically a firm, shiny, flesh-colored or bluish red bump. The bumps tend to grow rapidly without causing pain or tenderness.

Although Merkel cell carcinoma can affect any part of the skin, it is most common on skin that has been chronically exposed to sunlight (for example, the face and arms).

Merkel Cell Carcinoma
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This photo shows a red Merkel cell carcinoma on the sun-exposed cheek of a 90-year-old person.
DR P. MARAZZI/SCIENCE PHOTO LIBRARY

Diagnosis of Merkel Cell Carcinoma

  • Biopsy

A biopsy is done to confirm the diagnosis of Merkel cell carcinoma. During this procedure, a small piece of skin is removed and examined under a microscope.

In most people, the cancer has already spread by the time the diagnosis has been made, so the prognosis for Merkel cell carcinoma is poor.

Treatment of Merkel Cell Carcinoma

  • Surgical removal of the tumor

  • Usually radiation therapy and removal of lymph nodes

  • Sometimes chemotherapy

Treatment of Merkel cell carcinoma usually involves surgery to remove the tumor, often followed by radiation therapy, removal or biopsy of lymph nodes, or both.

If cancer has spread or returns, chemotherapy may be recommended.

Prevention of Merkel Cell Carcinoma

Because Merkel cell carcinoma is caused by sun exposure, people can help prevent this cancer by doing the following, starting in early childhood:

  • Avoiding the sun: For example, seeking shade, minimizing outdoor activities between 10 AM and 4 PM (when the sun’s rays are strongest), and avoiding sunbathing and the use of tanning beds

  • Wearing protective clothing: For example, long-sleeved shirts, pants, and broad-brimmed hats

  • Using sunscreen: At least sun protection factor (SPF) 30 with UVA and UVB protection used as directed and reapplied every 2 hours and after swimming or sweating but not used to prolong sun exposure

More Information

The following English-language resources may be useful. Please note that THE MANUAL is not responsible for the content of these resources.

  1. Merkelcell.org: A resource to help people find access to Merkel cell specialists and other patient resources

  2. American Cancer Society: Merkel Cell Skin Cancer: Information about Merkel cell carcinoma, including detection, prevention, treatment options, and other resources

  3. The Skin Cancer Foundation: Merkel Cell Carcinoma Overview: Information about Merkel cell carcinoma, including detection, prevention, treatment options, and other resources

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