Merkel Cell Carcinoma cases are reviewed by a multi-disciplinary tumor board at Saint John’s Cancer Institute and Health Center to individualize effective treatment plans.

What is Merkel Cell Carcinoma?

Merkel cell carcinoma (MCC) is a rare and potentially aggressive form of skin cancer that forms in the outer layer of skin. It appears as flesh-colored or a deep-red nodule on surface of the skin.

Long-term sun exposure or a weak immune system may increase your risk of developing Merkel cell carcinoma. MCCs are common on the face, neck, or head where UV exposure is the greatest, and most often develops in older people. MCCs are also referred to as neuroendocrine carcinoma of the skin. Though MCC can grow and spread rapidly, it accounts for less than 1 percent of total skin cancers diagnoses and is generally treatable and curable if caught in the early stages.

What does Merkel Cell Carcinoma look like?
Merkel Cell Carcinoma appears as flesh-colored or a deep-red nodule on surface of the skin.

What causes Merkel Cell Cancer?

The causes of Merkel cell cancer are not certain. Like other skin cancers, such as melanoma and squamous cell carcinoma, UV exposure is a major risk factor.

What are Merkel Cell Carcinoma symptoms?

Merkel cell cancers often present as a painless growth that appear on areas of the body that are sun exposed. Though growths are often flesh toned, they can be different colors and vary in size.

What are the risk factors of Merkel Cell Carcinoma?

There are serval factors that can foster MCC. Having a weakened immune system, being a recipient of an organ transplant, having HIV, or taking immune-suppression drugs, as well as older patients can present with higher risk. There is also a common skin virus, called Merkel polyomavirus, which is found in approximately 80% of tested tumors. However, it is not known if the polyomavirus causes MCC. To date, there is no genetic link that has been found to increase one’s risk of developing Merkel Cell Carcinoma.

Risk Factors of Merkel Cell Carcinoma

  • Heavily sun-exposed skin (UV light exposure)
  • Weakened immune systems (organ transplant patients and HIV patients)
  • Infection with Merkel cell polyomavirus (MCV)
  • Advanced age
  • Men are 2-times more likely to have it compared with women

Our team will determine the best course of treatment for you.

How is Merkel Cell Carcinoma Diagnosed?

At the Saint John’s Cancer Institute, we are fortunate to have all the required specialists. Our team will determine the best course of treatment for you, including performing a physical examination of your skin for unusual moles, freckles, pigmented spots, and other growths.

Biopsy involves removing a sample of suspicious skin or growth, which is analyzed in a laboratory to identify signs of cancer. Once cancer has been identified, it is important to determine its extent.

Multidisciplinary Melanoma Team - Saint Johns Cancer Institute
The multidisciplinary team at Saint John’s Cancer Institute includes experts in melanoma surgery, medical oncology, radiation, and immunology.

Sentinel node biopsy

A sentinel node biopsy is a procedure developed by Saint John’s Cancer Institute (formerly the John Wayne Cancer Institute) that is used worldwide to determine if cancer has spread to the lymph nodes.  Using a special dye at the site of the cancer, it can be tracked through the lymphatic system to see which nodes are receiving the dye first. This is a primary method for identifying the lymph nodes should be removed and tested.

Imaging tests

To determine if the cancer has spread to the trunk and organs, chest X-ray and CT may be recommended.  Other imaging tests such as a positron emission tomography (PET) scan may be needed. An octreotide scan is a test that uses an injection of a radioactive tracer to check for the spread of cancer cells.

If you have been diagnosed with Merkel Cell Carcinoma, optimal treatment will require the expertise of a multidisciplinary team of cancer specialists, such as the cancer team at Saint John’s Health Center. This may involve doctors in dermatology, surgical oncology, radiation oncology, medical oncology, plastic surgery, and pathology.

Merkel Cell Carcinoma Treatment

Treatment will usually include surgery to remove the Merkel cell tumor and a biopsy of the lymph nodes to determine if the cancer has spread. Prior to surgery, radiologic scans may be recommended to better understanding the size and extent of the tumor beneath the skin. Surgery is generally performed on an outpatient basis. Radiation therapy may be recommended for patients who have high-risk lesions—tumors whose genetic profile and growth speed indicate a greater likelihood of metastasis (cancer spread).

Patients whose Merkel cell cancer has spread beyond their lymph nodes into their organs, such as with later-stage cancers, are likely to require other medical treatments. For Merkel cell carcinoma that has spread, but is still confined within the arm or leg, immunotherapy may be recommended.


Mohs Surgery - Saint John's Cancer Institute
Mohs Surgery involves surgically removing thin layers of the skin to reveal the extent and location of the cancer.

Surgical excision of the affected tissue removes the cancerous lesion and a surrounding margin of healthy skin. This helps to reduce the risk of recurrence. The extent of the margin is determined by microscopic examination to verify the absence of cancer cells in the surrounding margin.  Surgery is typical for basal cell carcinomas in areas where they are less likely to recur.

Mohs Surgery

Mohs surgery is a specific method of excision designed to conserve as much normal tissue as possible. During Mohs surgery, the cancer is removed layer by layer, which allows examination of each layer under a microscope until no abnormal cells remain. This guides the direction and depth of the surgery, thereby removing the entire growth while avoiding healthy skin. If your basal cell carcinoma is larger and has an elevated risk of recurring, extends deeper, or is located on your face, Mohs surgery may be recommended.

If you are unable to undergo surgery, or if you have decided against having surgery, the oncologist may recommend other types of treatment.

Radiation therapy

Radiation therapy uses high-energy beams, such as X-rays and protons, that kill cancer cells by disrupting their DNA. By focusing the beams to the target area, therapeutic result is maximized while reducing side effects.  Radiation therapy can be given after surgery to help reduce the chance of recurrence and may be used when surgery is not an option.

Targeted Therapy

Targeted drug therapy may be recommended by the oncologist and works by taking advantage of genetic and molecular flaws within cancer cells. By blocking the cancer’s ability to sustain itself, it shrinks and dies. Targeted therapy drugs may be considered after other treatments or when those treatments are not possible.


Chemotherapy drugs are designed to kill cancer cells. It might be an option when other treatments have not helped. Can be given orally, intravenously, or in other ways while doses are carefully selected to target the specific type and stage of the cancer.

Saint John's Cancer Institute - Melanoma Research Specialists
Saint John’s Cancer Institute researches and develops innovative treatments for patients.

How to Prevent Merkel Cell Carcinoma

Chronic exposure to sun light is one of the highest risk factors in the development of basal cell cancers.

Prevention methods include:

  • Avoid the sun between 10AM to 4PM when UV radiation is the strongest.
  • Avoid using tanning beds.
  • Wear sun protective clothing and hats.
  • Use a broad-spectrum sunscreen (30 SPF or greater) if outside for extended periods.
  • See a dermatologist once a year for a head-to-toe skin examination.

If you have questions regarding Merkel Cell Carcinoma or would like an expert second opinion, please call today or click here to schedule an appointment.