Merkel Cell Carcinoma: Symptoms, Causes, Diagnosis, Treatment, and Prevention

What Is Merkel Cell Carcinoma?

What Is Merkel Cell Carcinoma?
Klaus D. Peter/Wikimedia Commons
Merkel cell carcinoma (MCC) is a rare form of skin cancer that typically appears as a painless pink, red, or purple bump on the skin.

If it metastasizes, it can spread to distant organs like the lungs, brain, and bones.

The bump that characterizes MCC tends to grow quickly. Knowing what to look for and catching it early will ensure the best outcome.

Signs and Symptoms of Merkel Cell Carcinoma

The shape and color of MCC nodules are less distinctive than other skin cancers. In fact, they may be mistaken for other skin issues, such as bug bites, sores, cysts, styes, or pimples.

 Often, it is only the speed with which these lesions grow that attracts the attention of patients and their doctors.
The lesions most commonly appear on areas of the skin that get the most sunlight, such as the face, head, or neck, though they can appear anywhere on the body.

A bump caused by MCC is likely to be:

  • Located on the face, head, neck, or arms
  • Firm and dome-shaped or raised
  • Pink, red, red-brown, or purple in tone or matching the skin’s color
  • Painless
  • Fast-growing, usually becoming noticeably bigger in a few weeks to months
  • A growing sore that may bleed
The appearance of the bump can vary some by race and color of skin. On pale skin, it tends to appear on the neck and head. On darker skin tones, the lesions tend to appear on the legs.

Causes and Risk Factors of Merkel Cell Carcinoma

Researchers once believed that MCC started in the Merkel cells that make up part of the top layer of skin. Despite the name, scientists no longer believe this to be the case, though they’re still not sure what exactly causes MCC in most cases.

What’s known is that cancer develops due to changes in the DNA of cells. Under normal circumstances, the coding of the DNA tells the cells when to reproduce and when to die. DNA mutations alter the life cycle of the cells, causing them to grow out of control.

Researchers still do not fully understand what causes these DNA changes to occur, but they have discovered that a virus, known as Merkel cell polyomavirus, may cause MCC in some cases. The virus lives on the skin of most people without any signs or symptoms — and without ever developing into MCC.

Just how this virus triggers skin cancer in some people and not others has yet to be determined, but researchers have identified a number of factors that markedly increase your risk. These include:

  • Excessive Exposure to UV Light Chronic, unprotected exposure to UV light from the sun or tanning beds damages the DNA of genes that control skin-cell growth.
  • Older Age Though MCC can occur at any age, your risk increases as you get older. The average age of diagnosis is 74.

  • A Weakened Immune System If your immune system is suppressed (as a result of HIV, chronic leukemia, or immunosuppressive drugs), you have a higher risk of developing MCC.
  • Light Skin Color MCC is more common in lighter skin complexions than darker skin tones, but it can occur in anybody. More than 9 out of 10 people with MCC have white or lighter skin.
  • Sex Males are more likely than females to develop MCC.
  • Previous Skin Cancer People with a history of skin cancer have an increased risk of MCC.

How Is Merkel Cell Carcinoma Diagnosed?

If you develop any spot, sore, bump, or stye that grows quickly, you should schedule an appointment with your primary care doctor or a dermatologist as soon as possible.

The initial part of the diagnosis will involve a physical examination as well as a review of your medical history. Your doctor will likely ask about your symptoms and when they started, and about any previous cancer history.

Blood tests aren’t used to diagnose MCC.

 To confirm a diagnosis of MCC, your doctor will need to get a skin biopsy. This procedure involves removing a small piece of the tissue so it can be viewed under a microscope by a pathologist to check for signs of cancer.

Staging Merkel Cell Carcinoma

To determine staging, a doctor may recommend the following tests.

  • A lymph node biopsy, to see if the cancer has spread to nearby lymph nodes.
  • Imaging tests, such as an X-ray, magnetic resonance imaging (MRI), computed tomography (CT) scan, or positron emission tomography (PET) scan of your body to find out if the cancer has spread to other areas.
There are two types of staging when it comes to MCC:

  • Clinical Stage This stage is based on imaging tests, physical exam, and the results of a biopsy. The clinical stage is helpful in planning treatment.
  • Pathological Stage This type of staging is based on pathology results after surgery and is done to remove more tissue from around the tumor, as well as from nearby lymph nodes to check for cancer.
For pathological staging, doctors follow a numerical staging system ranging from 0 to 4. The higher the number, the more the cancer has spread. Each number stage is based on the TNM system that focuses on three criteria:

  • T, which refers to the location and size of the tumor
  • N, which refers to the number of lymph nodes involved
  • M, for metastasis, means the tumor has spread to distant parts of the body
Here is a breakdown of the stages of MCC.

  • Stage 0 The cancer only affects the top layer of skin and has not spread to local tissue or lymph nodes.
  • Stage 1 The tumor is no more than 2 centimeters (cm) and has not spread to the lymph nodes or distant parts of the body.
  • Stage 2 The cancer is either larger than 2 cm across or has spread to nearby tissues, but it has not affected the lymph nodes or spread to distant areas.
  • Stage 3 The tumor may be of any size or may have spread to nearby tissues. The cancer has spread to nearby lymph nodes, but has not yet metastasized to distant areas of the body.
  • Stage 4 The tumor may be any size and may have grown into nearby tissue. It may or may not affect the nearby lymph nodes. The cancer has spread to distant parts of the body.

How Is Merkel Cell Carcinoma (MCC) Treated?

Treatment for MCC depends on the tumor’s size, location, spread, and lymph node involvement.

Localized MCC

Early-stage or localized MCC can usually be successfully treated with wide excision surgery to remove the cancer and some of the healthy cells around it. If the lesion is in a difficult location, a surgeon may choose Mohs micrographic surgery (in which the lesion is removed and examined in layers until no cancer is found).
If surgery is not a good option, radiation therapy, which uses high-energy beams to kill cancer cells, may be used to treat the MCC lesion. Radiation may also be used after surgery to ensure that any remaining cancer cells are destroyed.

MCC With Lymph Node Involvement

If the MCC has spread to the lymph nodes, the nodes may need to be removed surgically. This is in addition to any method used to treat the MCC lesion itself, such as wide excision surgery.

Recurring MCC

If MCC returns, the treatment will be similar to the first time. For the lesion itself, a surgeon may remove it using wider margins, meaning they will take more of the healthy skin along with the lesion. They may follow this with radiation.

Metastatic MCC

Metastatic MCC is harder to treat and will require systemic treatment, meaning treatments that affect the whole body. Immunotherapy, which helps the body’s own immune cells recognize and destroy cancer cells, is a popular option for treating MCC that has spread to distant organs.

One class of immunotherapy drugs, called checkpoint inhibitors, are showing promise in the treatment of MCC. Checkpoint inhibitors turn on the immune system against cancer cells by blocking a “checkpoint” that normally restrains the immune system. Studies suggest that checkpoint inhibitors can help shrink MCC tumors in many patients and that responses, when they occur, tend to be long lasting.
Several checkpoint inhibitors are currently available for people with MCC:
A number of other promising immunotherapy treatment approaches, including other checkpoint inhibitors and infusions of immune cells, are also being investigated for MCC in clinical trials.
Researchers are also studying the use of hormone-like therapies, oncolytic virus therapy (altering viruses to attack and kill cancer cells), targeted therapies, and different combinations of therapies for the treatment of MCC.
Chemotherapy is not typically used for MCC unless someone with the disease has not responded to any of the available options, or the cancer is very widespread.

To learn more about active MCC clinical trials, eligibility criteria, and location sites, visit the National Institutes of Health website ClinicalTrials.gov.

Prevention of Merkel Cell Carcinoma

There are a number of measures you can take to reduce your risk of developing MCC (as well as all skin cancers). It’s never too late to start. Though taking these steps can help reduce your risk, they do not guarantee you will never get MCC.

  • Limit UV exposure. You can practice prevention every day by wearing protective hats and clothing, avoiding the midday sun (between 10 a.m. and 3 p.m.) and tanning beds, and using broad-spectrum sunscreen with an SPF of at least 30 or higher, even on cloudy days. Reapply sunscreen every two hours when swimming or sweating.

  • Keep an eye out. MCC lesions don’t have the dramatic look or color of other skin cancers. That’s why it’s so important to closely examine your skin from head to toe once a month, including areas that get a lot of sun exposure like the neck, top of your head, face, legs, and other areas frequently exposed to sunlight. If you notice a new or unusual spot or a raised bump that seems to be growing, contact your doctor right away. Also, check less noticeable areas, including between your toes, on the soles of your feet, buttocks, and genitals.

  • Get screened. See a dermatologist at least once every year for a professional skin exam.

If you’ve been treated for MCC, you can take steps to prevent recurrence by doing the following:

  • Follow up regularly with your dermatologist once treatment is complete. Stick to the exam schedule your doctor recommends. It's the best way to quickly detect a recurrence.
  • Play close attention to the site and surrounding region. MCC can return suddenly. Contact your medical team immediately if you see any suspicious changes.
  • Consider getting the blood test that can help pick up recurrences early. The Merkel polyomavirus serology test measures antibodies to the Merkel polyomavirus in the blood. It can help pick up recurrences of MCC early, when they can be most effectively treated.

Lifestyle Changes for Merkel Cell Carcinoma (MCC)

At this point, not much is known about what you can do to help prevent recurrence if you have MCC or have been treated for it in the past.

If you have a weakened immune system, following all treatment recommendations can help reduce your risk of death due to MCC. Also, continuing to limit exposure to UV light may reduce your risk of other skin cancers. Regular skin exams can help catch recurring or different skin cancer cases early, when they are generally easier to treat.

While not specific to MCC, widely accepted advice for overall good health and cancer prevention include:

  • Not smoking
  • Being physically active
  • Eating a nutritious diet
  • Maintaining a healthy weight

Merkel Cell Carcinoma Prognosis

According to the American Cancer Society, the five-year survival rate for people with localized MCC (cancer that has not spread), is 79 percent.

For regional MCC (when the cancer has spread outside the skin to nearby lymph nodes or other structures), the five-year survival rate falls to 66 percent. If MCC has spread to distant organs, the survival rate is 31 percent.

The combined overall survival rate is 69 percent.

While survival rates can give you an idea of how long other people have lived based on what stage their cancer was at diagnosis, they can’t tell you how long you will live. Other factors, such as your age and overall health, as well as how well the cancer responds to treatment, also play a significant role in your prognosis.

Moreover, current survival statistics are based on outcomes of people diagnosed with MCC between 2015 and 2021. Thanks to new and better treatments, people now being diagnosed with MCC may have a better outlook.

Complications of Merkel Cell Carcinoma

One of the biggest risks of MCC is that it may spread either to local lymph nodes or to distant organs. Even with treatment, this can still occur.

MCC can spread to the:

  • Bones
  • Lungs
  • Brain
  • Liver
Life with MCC can also cause emotional or mental distress. Addressing your mental health through support groups or counseling may be helpful.

Research and Statistics: Who Gets Merkel Cell Carcinoma?

Skin cancer is the most common form of cancer in the United States.

Though MCC is much less common than other types of skin cancer — roughly 30 to 40 times less common than melanoma — incidence is on the rise, having quadrupled in the past few decades.

 According to the American Cancer Society, roughly 3,000 new cases of MCC are diagnosed annually in the United States.

Some of the uptick in MCC is likely because lab tests to diagnose MCC have become more accurate. The fact that people are living longer may be another factor, as well as the lack of regular sun protection used by people over age 65.

Support for People With MCC

Support for MCC can take several forms, including patient advocacy groups, counseling or therapy, financial support, and survivor groups.

Neuroendocrine Tumor Research Foundation

This patient-founded organization connects people with different types of support for MCC and other skin cancers. This includes financial assistance, patient advocacy groups, in-person and online support groups, and medication assistance.

American Cancer Society

You can join the Cancer Survivors Network, an online support community, to connect with other survivors and share your journey with people who understand.

You can also ask your dermatologist, oncologist, or other healthcare team members about local support groups in your area or any recommendations for additional help. Many clinics and hospitals have in-house or recommended social workers who can help connect you with support groups, financial aid, advocacy groups, and other helpful resources.

The Takeaway

  • Merkel cell carcinoma (MCC) is a rare, aggressive form of skin cancer that often does not have very obvious lesions. Rapidly changing and painless areas of skin are the most common symptom.
  • MCC is most common in people with lighter skin tones, men, and people older than 70.
  • Treatment typically involves the removal of the lesion. More advanced cases may require systemic treatments and the removal of affected lymph nodes.
  • Prognosis is generally best for MCC when it’s caught early and when it hasn't spread to other areas of the body, but there is always a chance it will come back. Continual monitoring of the skin as well as limiting UV exposure may prevent recurrence.

Resources We Trust

EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
  1. Skin Cancer Types: Merkel Cell Carcinoma Signs & Symptoms. American Academy of Dermatology Association.
  2. Merkel Cell Carcinoma. Mayo Clinic. January 10, 2025.
  3. Causes of Merkel Cell Carcinoma. MerkelCell.org. October 30, 2025.
  4. Merkel Cell Carcinoma Risk Factors. The Skin Cancer Foundation. April 2025.
  5. Key Statistics for Merkel Cell Carcinoma. American Cancer Society. January 10, 2025.
  6. Tests for Merkel Cell Carcinoma. American Cancer Society. January 10, 2025.
  7. Merkel Cell Carcinoma (MCC) Stages. American Cancer Society. January 10, 2025.
  8. Annual Exams. Skin Cancer Foundation.
  9. Disease Recurrence. MerkelCell.org. October 30, 2025.
  10. Serology test. MerkelCell.org. October 30, 2025.
  11. Living as a Merkel Cell Carcinoma (MCC) Survivor. American Cancer Society. January 10, 2025.
  12. Survival Rates for Merkel Cell Carcinoma. American Cancer Society. July 27, 2025.
  13. Melanoma of the Skin Statistics. Centers for Disease Control and Prevention (CDC). June 2025.
  14. What Is Merkel Cell Carcinoma? MerkelCell.org. October 30, 2025.

Blair Murphy-Rose, MD

Medical Reviewer

Blair Murphy-Rose, MD, is a board-certified dermatologist in New York City and the founder of Skincare Junkie. She is an accomplished cosmetic, medical, and surgical dermatologist, specializing in leading-edge facial rejuvenation techniques, including injectable fillers and botulinum toxin injections, advanced laser procedures, noninvasive body contouring, and removing lumps and bumps with precision. She is an expert in the treatment and detection of medical conditions, including skin cancer, acne, rosacea, eczema, and psoriasis. Dr. Rose believes in a comprehensive approach to skin health and incorporating a skin-care routine tailored specifically for each individual and utilizing a wide array of tools to target specific skin concerns.

Rose has been published in peer-reviewed journals, including the Journal of the American Academy of Dermatology, Dermatology Surgery, and Pediatric Dermatology, and has been featured in numerous publications, including Vogue, Elle, Allure, Cosmopolitan, Self, Women’s Health, The Wall Street Journal, and The New York Times.

Jenna Fletcher

Jenna Fletcher

Author

Jenna Fletcher is a writer with many years of experience in the health and wellness space. She is based in Coopersburg, Pennsylvania, where prior to transitioning to writing, Jenna taught group fitness classes, Pilates mat classes, and dance classes, and was a personal trainer. She is very interested in general health and wellness, but since experiencing a stillborn twin, Jenna has written extensively about women's health issues, including pregnancy complications and mental healthcare. Her work has appeared on a variety of outlets across the web including HuffPost, Insider, Medical News Today, Healthline, and more.