What is merkel cell carcinoma?
Merkel cell carcinoma is a rare type of skin cancer that usually appears as a flesh-coloured or bluish-red nodule, often on the face, head, or neck. It is also called neuroendocrine carcinoma of the covering.
It develops most often in older people. Long-term sun exposure or a weak immune system can increase your risk of developing cancer. It tends to grow rapidly and spread rapidly to other parts of your body. Treatment options often depend on whether cancer has spread beyond the skin.
Types of skin cancer
- Cutaneous T-cell lymphoma
- Dermatofibrosarcoma protuberans (DFSP)
- Merkel cell carcinoma
- Sebaceous carcinoma
Symptoms of merkel cell carcinoma
The first sign is typically a fast-growing, painless nodule (tumor) on the skin. The nodule may be skin-coloured or it may appear in shades of red, blue, or purple. Most Merkel cell carcinomas appear on the face, head, or neck, but they can develop anywhere on the body, even in areas not exposed to sunlight.
Causes of merkel cell carcinoma
Merkel cell carcinoma begins in Merkel cells. Merkel cells are found at the base of the outermost layer of your skin (epidermis). Merkel cells are connected to nerve endings in the skin that are liable for the sense of touch.
Investigators recently discovered that a common virus plays a role in causing most cases. The virus (Merkel cell polyomavirus) lives on the skin and causes no signs or symptoms. How this virus causes Merkel cell carcinoma has not yet been determined. Since the virus is very common and Merkel cell carcinoma is very rare, other risk factors are likely to play a role in the development of this cancer.
Factors that can increase your risk of Merkel cell carcinoma include:
- Excessive exposure to natural or artificial sunlight: Being unprotected to ultraviolet light, such as light from the sun or tanning beds, increases the risk of Merkel cell carcinoma. Most Merkel cell carcinomas appear on skin surfaces that are frequently exposed to the sun.
- A weakened immune system: People with weakened immune systems, counting those with HIV infection, those taking drugs that overpower the immune response, or those with chronic leukemias, are more likely to develop Merkel cell carcinoma.
- History of other skin cancers: Merkel cell carcinoma is related to the progress of other skin cancers, such as basal cell or squamous cell carcinoma.
- Old age: Your danger of Merkel cell carcinoma increases as you age. This cancer is most common in people over the age of 50, although it can occur at any age.
- Light skin colour. Merkel cell carcinoma usually occurs in people who have light-coloured skin. Whites are much more likely to be affected by skin cancer than blacks.
Cancer ranges to other parts of the body.
Even with treatment, Merkel cell carcinoma frequently spreads (metastasizes) outside the skin. Merkel cell carcinoma tends to travel to nearby lymph nodes first. Later, it can spread to your brain, bones, liver, or lungs, where it can interfere with the effectiveness of these organs. Cancer that has metastasized is tougher to treat and can be fatal.
While exposure to sunlight has not been shown to cause Merkel cell carcinoma, it is considered a risk factor for this cancer. Reducing your exposure to the sun can lower your risk of skin cancer. Try:
- Avoid the sun during peak hours: Avoid sun exposure as much as possible during the brightest hours of the day, usually, 10 a.m. at 4 p.m. Move your outdoor activities to an earlier time in the morning or later in the day.
- Protect your skin and eyes: Wear a wide-brimmed hat, tight-knit clothing, and sunglasses with ultraviolet (UV) protection.
- Apply sunscreen generously and often: Use an extensive spectrum sunscreen with an SPF of at least 30, even on cloudy days. Apply sunscreen kindly and reapply every two hours, or more often if you’re swimming or sweating.
- Watch for changes: If you notice a mole, freckle, or lump that changes in size, shape, or colour, talk to your doctor. Most skin nodules never turn into cancer, but getting cancer in its early stages increases the chances that treatment will be successful.
Merkel cell carcinoma diagnosis
The tests and procedures used to diagnose Merkel cell carcinoma include:
- Physical exam: Your doctor will examine your skin for moles, freckles, pigmented spots, and other unusual growths.
- Extraction of a suspicious skin sample: During a process called a skin biopsy, your doctor removes the tumor or a sample of the tumor from your skin. The sample is analyzed in a laboratory to look for signs of cancer.
Determining the extent
Your doctor may use the following tests to help determine if cancer has spread beyond your skin:
- Sentinel node biopsy: A sentinel node biopsy is a procedure to find out if cancer has spread to the lymph nodes. This procedure contains injecting a dye near cancer. Then the dye 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 cancer cells under a microscope.
- Imaging tests: Your doctor may recommend a chest X-ray and CT scan of your chest and abdomen to help determine if cancer has spread to other organs.
Your doctor may also consider other imaging tests, such as a positron release tomography (PET) scan or an octreotide scan, a test that uses an injection of a radioactive tracer to check for the spread of cancer cells.
Merkel cell carcinoma treatment
Treatments for Merkel cell carcinoma may include:
- Surgery: During surgery, your doctor removes the tumor along with a border of normal skin that surrounds it. If there is evidence that cancer has spread to lymph nodes in the area of the skin tumor, those lymph nodes are removed (lymph node dissection).
The surgeon usually uses a scalpel to remove cancer. During Mohs surgery, thin layers of tissue are methodically removed and checked under a microscope to see if they contain cancer cells. If cancer is found, the surgical process is repeated until the cancer cells are no longer visible in the tissue. This type of surgery removes less normal tissue, reducing scarring, but ensuring a tumor-free edge of the skin.
- Radiation therapy: It involves guiding high-energy beams, such as X-rays and protons, at cancer cells. During radiation treatment, you are placed on a table and a large machine moves around you, directing the rays to precise points on your body.
Radiation therapy is sometimes used after surgery to kill cancer cells that remain after the tumor is 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.
- Immunotherapy: In immunotherapy, drugs are used to help your immune system fight cancer. Most often, immunotherapy is used to treat Merkel cell carcinoma that has a feast on other areas of your body.
- Chemotherapy: Chemotherapy uses drugs to kill cancer cells. Chemotherapy drugs can be given through a vein in your arm or taken as a pill, or both.
Chemotherapy is not used often, but your physician may mention it if your Merkel cell carcinoma has spread to your lymph nodes or other organs in your body, or if it has returned despite treatment.