Merkel Cell Carcinoma
What is Merkel cell carcinoma?
Merkel cell carcinoma is a rare and aggressive type of skin cancer that can be life-threatening. It develops in Merkel cells found in your skin’s outer layer (your epidermis).
Exposure to ultraviolet (UV) light and other risk factors can cause these cells to become cancerous and grow uncontrollably. Merkel cell carcinoma tends to spread quickly to other parts of your body and often comes back after treatment.
What are Merkel cells?
Merkel cells are found deep in your epidermis (top layer of your skin). The cells are a type of neuroendocrine cell that has both nervous system and endocrine system functions. They sit near nerve endings that provide sense of touch and they have substances that act like hormones. German physician Friedrich Merkel first described these cells in the late 1800s.
How common is Merkel cell carcinoma?
Merkel cell carcinoma is a very rare type of skin cancer, affecting approximately 3,000 Americans every year.
However, the number of people receiving a Merkel cell carcinoma diagnosis is steadily increasing. This increase may be due to improved diagnostic tests. The condition also tends to affect people older than 70. As people live longer, they may be more likely to develop this cancer.
What are other names for Merkel cell carcinoma?
You may also hear these terms to refer to Merkel cell carcinoma:
- Merkel cell cancer.
- Neuroendocrine carcinoma of the skin.
- Trabecular cancer.
Symptoms and Causes
What causes Merkel cell carcinoma?
UV rays from sun exposure or artificial light sources like tanning beds cause most types of skin cancer, including Merkel cell carcinoma. UV radiation can damage the genetic makeup, or DNA, of skin cells.
Eight in 10 people with Merkel cell carcinoma have the Merkel cell polyomavirus (MCP). But most people infected with MCP don’t develop Merkel cell carcinoma. This common childhood virus doesn’t cause symptoms, and there isn’t a way to screen for it. Medical experts are still trying to determine how and why the virus causes skin cancer in some people.
Research suggests a weakened immune system may not be able to suppress the virus. As a result, the virus causes skin cells to make a protein that turns off the genes that normally suppress the growth of tumors.
What are the risk factors for Merkel cell carcinoma?
People of all ages, genders and skin colors can get Merkel cell carcinoma. But men who are fair-skinned and over 50 are most at risk.
Other risk factors include:
- Having other types of skin cancer like basal cell carcinoma, squamous cell carcinoma or melanoma.
- History of tanning bed use or severe sunburns.
- Receiving light therapy (phototherapy) to treat psoriasis or other skin diseases.
- Weakened immune system due to chronic lymphocytic leukemia, HIV and AIDS, or other conditions.
- Taking organ transplant medications or immunosuppressants.
What are the signs of Merkel cell carcinoma?
Tumors from Merkel cell carcinoma typically appear on sun-exposed areas of skin. You may notice a shiny or pearly lump on an area of skin that gets a lot of sun exposure.
The lumps most commonly appear on your face, neck, arms or eyelids. People with darker skin can often get these tumors on their legs. For people who are younger, the lump appears on their torso. The lump may break open into a wound or sore, too.
The lump may be:
- About the size of a dime and growing quickly.
- Dome shaped or raised.
- Similar to a pimple (acne) or insect bite.
- Skin colored or red, purple or bluish-red.
- Tender or sore.
What are the complications of Merkel cell carcinoma?
Merkel cell carcinoma is an aggressive cancer that spreads quickly to other parts of your body. When cancer spreads from its primary site, you have metastatic cancer. Metastatic cancer is more difficult to treat.
Merkel cell carcinoma most commonly spreads to your lymphatic system (lymph nodes) first. From there, it may spread to other parts of your body like your bones, lungs, brain or other organs. Merkel cell carcinoma can be fatal.
Diagnosis and Tests
How is Merkel cell carcinoma diagnosed?
A dermatologist diagnoses and treats skin diseases like Merkel cell carcinoma. Seeing a skin cancer specialist is important because other conditions like benign (noncancerous) cysts, infected hair follicles (folliculitis) and styes can look similar to Merkel cell carcinoma.
Your healthcare provider will perform a full-body skin exam. They may feel for swollen lymph nodes, which can indicate infection or potential cancer spread. You’ll receive a skin biopsy of the tumor to check for cancer cells.
What are the stages of Merkel cell carcinoma?
Healthcare providers use cancer staging to determine the extent of cancer spread. Staging happens soon after diagnosis. The higher the stage number, the more severe the cancer spread.
Stage 0 Merkel cell carcinoma cancer only affects your skin’s outer layer. Stage IIIV (4) indicates the cancer is in distant organs.
What tests determine the stages of Merkel cell carcinoma?
You may get one or more of these tests to determine the cancer stage of Merkel cell carcinoma:
Management and Treatment
How is Merkel cell carcinoma treated?
Treatments for Merkel cell carcinoma depend on the cancer stage. Early-stage Merkel cell carcinoma (stages 0 to II ) responds better to treatments than late-stage (stages III and IIIV [3 and 4]) cancers.
Healthcare providers surgically remove Merkel cell carcinoma tumors. Surgical options include:
- Mohs surgery to remove the tumor and skin layers while preserving as much healthy tissue as possible.
- Wide local excision to remove the tumor and some surrounding healthy tissue.
- Lymph node dissection to surgically remove lymph nodes that have metastatic cancer cells.
What happens after surgery to treat Merkel cell carcinoma?
After surgery, you may need reconstructive surgery or a skin graft to repair and heal the treated area. You may also get cancer treatments to kill any lingering cancer cells in your body, such as:
Can you prevent Merkel cell carcinoma?
You can take these steps to protect yourself from sun damage and lower your risk of developing Merkel cell carcinoma:
- Apply a broad-spectrum sunscreen with a sun protection factor (SPF) of 60 every day even when indoors. Reapply sunscreen every two hours, especially when outdoors.
- Avoid going outside between 10 a.m. and 4 p.m. when the sun’s rays are strongest. Seek shade if you must be outdoors.
- Don’t use tanning beds or sunlamps.
- Dress in tightly woven clothes, long sleeves, a wide-brimmed hat and large sunglasses when outdoors.
- Learn how to do skin self-exams and contact your healthcare provider any time you notice skin changes.
Outlook / Prognosis
What is the outlook for someone with Merkel cell carcinoma?
Merkel cell carcinoma often returns after treatment. You may need to see your healthcare provider every three to four months for the first several years and get imaging scans to check for cancer recurrence.
Many factors — like your overall health, age and cancer stage — influence survival rates when you have Merkel cell carcinoma. Experts estimate that 3 out of 4 people who have localized Merkle cell carcinoma (cancer that hasn’t spread) are alive five years after diagnosis. That number drops to 1 in 4 when you have metastatic cancer. There are many clinical trials underway for new treatments for Merkel cell carcinoma.
When should I call the doctor?
Call your healthcare provider if you notice unexplained changes to your skin:
- New mole, changes to an existing mole or a mole that bleeds.
- Scaly or crusty skin lesions.
- Sores that don’t heal.
- Unexplained lumps, especially ones that itch, hurt or grow in size.
What should I ask my provider?
You may want to ask your healthcare provider:
- What caused Merkel cell carcinoma?
- What’s the best treatment for me?
- What steps can I take to prevent cancer recurrence (return)?
- Should I look for signs of complications?
A note from Cleveland Clinic
It’s understandably distressing to receive a skin cancer diagnosis like Merkel cell carcinoma. This cancer can spread quickly. It’s important to see your healthcare provider any time you notice changes to your skin. They’ll remove the tumor surgically and offer other treatments depending on the cancer stage. You’ll need regular follow-ups after treatment to check for cancer recurrence and spread.
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