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 areas of the body. To learn more about how cancers start and spread, see What Is Cancer?
Merkel cell carcinoma (MCC) is an uncommon type of skin cancer. It starts when cells in the skin called Merkel cells start to grow uncontrollably. This type of cancer can grow quickly and can be hard to treat if it spreads beyond the skin.
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 epidermis, which is the top layer of the skin. 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 cell carcinoma
Merkel cell carcinoma starts when Merkel cells grow out of control. Because Merkel cells are a type of neuroendocrine cell, 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. It’s much more likely than common skin cancers to spread to other parts of the body if not caught early, and it can be very hard to treat if it has spread.
These cancers most often start on sun-exposed parts of the skin, such as the face (the most common site), neck, and arms. But MCC can start anywhere on the body. Merkel cell tumors usually appear as firm, pink, red, or purple lumps or bumps on the skin. They are not usually painful, but they can grow quickly and can sometimes open up as ulcers or sores (see Signs and Symptoms of Merkel Cell Carcinoma).
While nearly all MCCs start on the skin, a very small portion start in other parts of the body, such as inside the nose or esophagus.
Other types of skin cancer
Basal and squamous cell carcinomas
These are by far the most common skin cancers. They rarely spread to other parts of the body, and usually can be cured with surgery. For more information on these cancers, see Basal and Squamous Cell Skin Cancer.
These cancers develop from melanocytes, the pigment-making cells of the skin. Melanomas are much less common than basal and squamous cell cancers, but they are much more likely to spread and be life-threatening if not caught at an early stage. Learn more in Melanoma Skin Cancer.
Less common types of skin cancer
Other, much less common types of skin cancer include:
- Kaposi sarcoma
- Lymphoma of the skin
- Skin adnexal tumors (tumors that start in the hair follicles or skin glands)
- Various types of sarcomas
Together, these types account for less than 1% of skin cancers.
Last Medical Review: April 13, 2015 Last Revised: May 23, 2016