Learn About Merkel Cell Carcinoma

What is Merkel cell carcinoma?

Merkel cell carcinoma (MCC) is a type of skin cancer that's not common but can spread quickly. It starts from special cells in the top layer of the skin called Merkel cells.¹ MCC usually looks like a painless, solid, shiny bump on the skin that may have a red, pink, or blue hue.² It often occurs on parts of the skin that are exposed to the sun.¹

Merkel cells were first identified in the late 1800s by a German doctor named Friedrich Merkel. These cells are believed to be a type of skin neuroendocrine cell because they have similarities to both nerve cells and hormone-producing cells. They are primarily located at the bottom of the skin's top layer (the epidermis) and are positioned near nerve endings. Merkel cells play a role in helping us feel light touch, allowing us to perceive the delicate details of an object's surface.¹

MCC is dangerous because it is more likely than common skin cancers to spread to other parts of the body, making it difficult to treat once it has spread. MCC often begins on sun-exposed skin, such as the face, neck, and arms, but it can develop anywhere on the body. These tumors typically appear as firm, pink, red, or purple lumps or bumps on the skin. While they usually don't cause pain, they grow rapidly and can occasionally turn into ulcers or sores. Although almost all MCCs start on the skin, a very small number originate in other parts of the body, such as inside the nose or throat.¹

What causes MCC?

While we understand some factors that can increase the risk of MCC, it's not fully clear how these factors cause the disease. Cancer results from DNA changes within cells. DNA contains our genes, which regulate cell functions, growth, and division. Changes in genes can lead to cancer. MCC doesn't appear to be inherited, and the DNA changes that cause it likely occur during a person's life, sometimes due to factors like sun exposure or Merkel cell polyomavirus (MCV) infection.³

Ultraviolet (UV) radiation from the sun can damage the DNA in skin cells, potentially initiating the development of cancer. MCV infection's role in MCC development is not entirely clear, but the virus can prompt cells to produce a protein, possibly contributing to MCC. The virus could thrive in individuals with weakened immune systems, increasing the risk of MCC. Scientists are studying the specific DNA changes in MCC cells to better understand the causes of the disease, which could lead to improved treatment strategies.³

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