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CLF - What is Merkel cell carcinoma (MCC)?

Merkel cell carcinoma, or MCC, is a rare and serious type of skin cancer. It happens when certain skin cells become cancerous and start growing out of control. 

These cells are supposed to turn into healthy Merkel cells, which help your skin sense things. But sometimes, while the cells are developing, they can become cancerous instead. Learn more about Merkel cells.

Fast-facts about MCC:

  • It usually appears as a bump on the skin (see symptoms and appearance) 
  • MCC is most common in people over the age of 65 (see causes and risk factors) 
  • There are about 3200 new MCC cases in the United States each year
  • It can be aggressive, so it is very important to see a doctor who specializes in MCC early on find a specialist
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CLF - What are Merkel Cells?

Everyone has Merkel cells. They are a type of cell found in the top layer of the skin, called the epidermis. 

Merkel cells help you to sense touch, such as textures or pressures. They also send information to your brain to help you understand what you’re feeling. Because they use special chemicals and hormones to communicate with your brain, Merkel cells are called neuroendocrine cells.

Merkel cells can be found all over your body, but are more common in places like:

  • Fingertips
  • Lips 
  • Face
  • Hair follicles (the skin that surrounds the root of hair)

Scientists are still learning about all the things Merkel cells do, but know they are important for our sense of touch.

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CLF - What causes MCC?

Merkel cell carcinoma (MCC) is usually caused by a very common virus called the Merkel cell polyomavirus. The virus itself is not a problem for most people; it can’t be spread to others, and most people who have this virus never develop MCC. However, in some cases, the virus can contribute to the cause of MCC when combined with other risk factors. 

The other cause of MCC is getting a lot of sun exposure over many years. People with lighter skin tones are more likely to get MCC from sun damage.

Here are some facts:

  • About 80% of MCC cases are caused by the virus in the United States
  • About 20% are caused by too much sun damage in the United States
  • People with weakened immune systems are at higher risk for MCC, but most people (~90%) who do get MCC do not have weakened immune systems