What Is Merkel Cell Carcinoma?

Cancer starts when cells begin to grow out of control. Cells in nearly any part of the body can become cancer, and can then spread to other parts of the body. To learn more see What Is Cancer?

Merkel cell carcinoma (MCC) is a rare type of skin cancer. It starts when cells in the skin called Merkel cells start to grow out of control. MCC tends to grow quickly and can be hard to treat if it spreads beyond the skin.

Merkel cells

Merkel cells are thought to be a type of skin neuroendocrine cell, because they share some features with nerve cells and hormone-making cells. Merkel cells are found mainly at the base of the top layer of the skin (the epidermis). These cells are very close to nerve endings in the skin. They help us sense light touch, which lets us do things like feel the fine details on an object’s surface.

Merkel cells were first described in the late 1800s by a German doctor named Friedrich Merkel.

 

Merkel cell carcinoma

Because Merkel cells are a type of neuroendocrine cell, Merkel cell carcinoma (MCC) is also sometimes called neuroendocrine carcinoma of the skin. Another name for MCC is trabecular carcinoma (or trabecular cancer).

MCC is much less common than most other types of skin cancer (see below), but it’s one of the most dangerous types. (The other dangerous skin cancer is melanoma.) It’s much more likely than common skin cancers (squamous and basal cell skin cancers ) to spread to other parts of the body, and it can be very hard to treat if it has spread.

These cancers most often start on skin that's exposed to the sun, like the face (the most common site), neck, and arms. But MCC can start anywhere on the body. Merkel cell tumors often look like firm, pink, red, or purple lumps or bumps on the skin. They usually don't hurt, but they're fast-growing and can sometimes open up as ulcers or sores (see Signs and Symptoms of Merkel Cell Carcinoma).

Nearly all MCCs start on the skin, but a very small portion start in other parts of the body, such as inside the nose or esophagus.

Other types of skin cancer

There are other, more common skin cancers. For more on these types of cancers, see Basal and Squamous Cell Skin Cancer and Melanoma Skin Cancer.

Less common types of skin cancer

Other, much less common types of skin cancer include:

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Merkelcell.org. Seattle Multidisciplinary MCC Team, University of Washington MCC Research, Fred Hutchinson Cancer Research Center, and the Seattle Cancer Care Alliance/Skin Cancer. What is a Merkel cell? Accessed at www.merkelcell.org/about-mcc/what-is-a-merkel-cell/ on July 28,  2018.

National Cancer Institute. Merkel Cell Carcinoma Treatment (PDQ®)–Patient Version. May 2, 2018. Accessed at www.cancer.gov/types/skin/patient/merkel-cell-treatment-pdq on July 23, 2018.

National Comprehensive Cancer Network, Clinical Practice Guidelines in Oncology (NCCN Guidelines®), Merkel Cell Carcinoma, Version 2.2018 -- June 15, 2018. Accessed at www.nccn.org/professionals/physician_gls/pdf/mcc.pdf on July 23, 2018.

 

Last Medical Review: October 9, 2018 Last Revised: October 9, 2018

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