Merkel cell carcinoma is a rare, aggressive form of skin cancer with a high risk of return (recurrence) and spread (metastasis), usually within two to three years of initial diagnosis. You can find more information below.
What is Merkel cell carcinoma?
Merkel cell carcinoma is a rare type of skin cancer that usually appears as a flesh-colored or bluish-red nodule on your face, head, or neck . Merkel cell carcinoma is also called neuroendocrine carcinoma .
Merkel cell carcinoma most often develops in older people. Prolonged sun exposure or a weak immune system can increase the risk of developing this cancer.
Merkel cell carcinoma tends to grow rapidly and spread quickly to other parts of your body. Treatment options often depend on whether the cancer has spread beyond the skin.
What causes Merkel cell carcinoma?
It is not clear what causes this type of carcinoma. This type of cancer begins in Merkel cells. Merkel cells are located at the base of the outermost layer of your skin (epidermis). Merkel cells are connected to nerve endings in the skin that are responsible for the sense of touch.
Researchers recently discovered that a common virus plays a role in most cases of Merkel cell carcinoma. This virus ( polyomavirus ) lives on the skin and does not cause any signs or symptoms. How this virus causes Merkel cell carcinoma remains to be determined. Given that the virus is so common and so rare for this type of carcinoma, other risk factors are likely to play a role in the development of this cancer.
Who is at risk?
Factors that can increase your risk of Merkel cell carcinoma include:
- Excessive exposure to natural or artificial sunlight: Exposure to ultraviolet light, such as light from the sun or tanning beds, increases your risk of Merkel cell carcinoma. Most of these carcinomas occur on skin surfaces that are frequently exposed to the sun.
- Weakened immune system: People with weakened immune systems – including those with HIV infection , those on immunosuppressant medications, or those with chronic leukemia – are more likely to develop Merkel cell carcinoma.
- History of other skin cancers: It is also associated with the development of other skin cancers such as Merkel cell carcinoma, basal cell carcinoma or squamous cell carcinoma .
- Old age: Your risk of Merkel cell carcinoma increases as you get older. This cancer is most common in people older than 50, but can occur at any age.
- Light skin colour: Merkel cell carcinoma usually occurs in people with fair skin. Whites are much more likely to be affected by this skin cancer than blacks.
What are the symptoms of Merkel cell carcinoma?
The first sign of Merkel cell carcinoma is usually a fast-growing, painless nodule (tumor) on your skin. The nodule may be skin-colored or appear in shades of red, blue, and purple. Most Merkel cell carcinomas occur on the face, head, or neck, but can develop anywhere on your body, even in areas not exposed to sunlight.
When should you see a doctor?
See your doctor if you notice a mole, freckle, or lump that changes in size, shape, or color, grows rapidly, or bleeds easily after minor things like washing and shaving your skin.
How is Merkel cell carcinoma diagnosed?
Tests and procedures used to diagnose this type of carcinoma include:
- Physical exam: Your doctor will examine your skin for unusual moles, freckles, pigmented spots, and other growths.
- Taking a suspicious skin sample: During a procedure called a skin biopsy , your doctor removes the tumor or tumor sample from your skin. The sample is analyzed in a laboratory to look for signs of cancer.
Determining the scope
Your doctor may use the following tests to help you determine if the cancer has spread beyond your skin:
- Sentinel node biopsy: A sentinel node biopsy is a procedure that determines whether cancer has spread to the lymph nodes. This procedure involves injecting dye into the area close to the cancer. The dye then flows through the lymphatic system to the lymph nodes. The first lymph nodes to receive the dye are called sentinel nodes. Your doctor removes these lymph nodes and looks for cancerous cells under a microscope.
- Imaging tests: Your doctor may recommend a chest X-ray and a computed tomography scan of your chest and abdomen to determine if the cancer has spread to other organs . Your doctor may also consider other imaging tests, such as a positron emission tomography (PET) scan or an octreotide scan. This is a test that uses an injection of a radioactive tracer to control the spread of cancer cells.
How is Merkel cell carcinoma treated?
Treatment of Merkel cell carcinoma may include:
During the surgery, your doctor removes the tumor along with the normal skin margin surrounding the tumor. If there is evidence that the cancer has spread to the lymph nodes at the site of the skin tumor, these lymph nodes are removed ( lymph node dissection ).
The surgeon usually uses a scalpel to cut through the cancer. In some cases, your doctor may use a procedure called Mohs surgery .
During Mohs surgery, thin layers of tissue are methodically removed and analyzed under a microscope to see if they contain cancer cells. If cancer is found, the surgical procedure is repeated until the cancer cells are no longer visible in the tissue. This type of surgery takes less normal tissue, thus reducing scarring.
Radiation therapy involves directing high-energy beams, such as X-rays and protons, at cancer cells. During radiation therapy, you are placed on a table, a large machine moves around you and guides the beams to precise points on your body.
Radiation therapy is also sometimes used after surgery to destroy any cancer cells that remain after the tumor has been removed.
Radiation can also be used as the sole treatment for people who choose not to have surgery. Radiation can also be used to treat areas where cancer has spread.
In immunotherapy, drugs are used to help your immune system fight cancer. Most often, immunotherapy is used to treat Merkel cell carcinoma that has spread to other parts of your body.
Chemotherapy uses drugs to kill cancer cells. Chemotherapy drugs can be administered through a vein in your arm, taken as a pill, or both.
Chemotherapy isn’t used as often, but your doctor may recommend it if your Merkel cell carcinoma has spread to the lymph nodes or other organs in your body and is recurring despite treatment.
Can Merkel cell carcinoma be prevented?
Although exposure to sunlight has not been proven to cause merkel cell carcinoma, it is considered a risk factor for this cancer. Reducing your exposure to the sun can reduce your risk of skin cancer. You can also try:
- Avoid the sun during peak hours: Avoid sun exposure during the strongest sunlight hours of the day (usually from 10 am to 4 pm). Take your outdoor activities early in the morning or later in the day.
- Protect your skin and eyes: Wear a wide-brimmed hat, tightly woven clothing, and sunglasses with ultraviolet (UV) light protection.
- Apply sunscreen liberally and often: Use a broad-spectrum sunscreen, even on cloudy days. Apply sunscreen generously and reapply every two hours, more often if swimming or sweating.
- Watch for changes: If you notice a mole, freckle, or lump that has changed in size, shape, or color, talk to your doctor. Most skin nodules never become cancer, but catching cancer in its early stages increases the chances of treatment being successful.
Merkel cell carcinoma complications
Even with treatment, this type of carcinoma often spreads (metastasizes) beyond the skin. It tends to travel to nearby lymph nodes first. It can then spread to your brain, bones, liver or lungs, where it can interfere with the functioning of these organs. Cancer that has metastasized is more difficult to treat and can be fatal.