This uncommon type of skin cancer develops from neuroendocrine cells (hormone-making cells that resemble nerve cells in some ways) in the skin. They are most often found on the head, neck, and arms but can start anywhere. These cancers are thought to be caused in part by sun exposure and in part by Merkel cell polyomavirus (MCV). About 8 out of 10 Merkel cell carcinomas are thought to be related to MCV infection. MCV is a common virus. Many people are infected with MCV, but it usually causes no symptoms. In a small portion of people with this infection,.
