Tests and procedures used to diagnose Merkel cell carcinoma include:

  • Physical exam. Your doctor will examine your skin for unusual moles, freckles, pigmented spots and other growths.
  • Removing a sample of suspicious skin. During a procedure 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 whether the cancer has spread beyond your skin:

  • Sentinel node biopsy. A sentinel node biopsy is a procedure to determine whether cancer has spread to your lymph nodes. This procedure involves injecting a dye near the cancer. The dye then flows through the lymphatic system to your lymph nodes.

    The first lymph nodes that receive the dye are called the 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 CT scan of your chest and abdomen to help determine whether 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 — a test that uses an injection of a radioactive tracer to check for the spread of cancer cells.


Treatments for Merkel cell carcinoma can include:

  • Surgery. During surgery, your doctor removes the tumor along with a border of normal skin surrounding the tumor. If there's evidence that the cancer has spread to lymph nodes in the area of the skin tumor, those lymph nodes are removed (lymph node dissection).

    The surgeon most often uses a scalpel to cut away 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 whether they contain cancer cells. If cancer is found, the surgical process is repeated until cancer cells are no longer visible in the tissue. This type of surgery takes out less normal tissue — thereby reducing scarring — but ensures a tumor-free border of skin.

  • Radiation therapy. Radiation therapy involves directing high-energy beams, such as X-rays and protons, at cancer cells. During radiation treatment, you're positioned on a table and a large machine moves around you, directing the beams to precise points on your body.

    Radiation therapy is sometimes used after surgery to destroy any cancer cells that remain after the tumor is removed.

    Radiation may also be used as the sole treatment in people who choose not to undergo surgery. Radiation can also be used to treat areas where the 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 spread to other areas of your body.
  • Chemotherapy. Chemotherapy uses drugs to kill the cancer cells. Chemotherapy drugs can be administered through a vein in your arm or taken as a pill or both.

    Chemotherapy is not used often, but your doctor may recommend 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.

Clinical trials

Explore Mayo Clinic studies testing new treatments, interventions and tests as a means to prevent, detect, treat or manage this condition.

Preparing for your appointment

If you have a mole, freckle or bump on your skin that concerns you, start by making an appointment with your doctor. If your doctor suspects that you may have skin cancer, you'll likely be referred to a skin specialist (dermatologist).

Because appointments can be brief, and because there's often a lot to discuss, it's a good idea to be well-prepared. Here's some information to help you get ready, and what to expect from your doctor.

What you can do

  • Write down any symptoms you're experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment.
  • Write down key personal information, including any major stresses or recent life changes.
  • Make a list of all medications, vitamins or supplements that you're taking.
  • Consider taking along a family member or friend. Sometimes it can be difficult to remember all the information provided during an appointment. Someone who accompanies you may remember something that you missed or forgot.
  • Write down questions to ask your doctor.

Your time with your doctor is limited, so preparing a list of questions can help you make the most of your time together. List your questions from most important to least important in case time runs out. For Merkel cell carcinoma, some basic questions to ask your doctor include:

  • What is likely causing my symptoms or condition?
  • Are there other possible causes for my symptoms or condition?
  • What kinds of diagnostic tests do I need? How are these tests performed?
  • What are my treatment options?
  • How will you check my response to treatment?
  • How likely is my condition to recur? What treatment options would be available in that case?
  • What follow-up tests will I need to monitor for recurrence?
  • I have other health conditions. How can I best manage them together?
  • Are there any restrictions that I need to follow?
  • Should I see a specialist? What will that cost, and will my insurance cover it?
  • Are there any brochures or other printed material that I can take with me? What websites do you recommend?

In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment.

What to expect from your doctor

Your doctor is likely to ask you a number of questions. Being ready to answer them may reserve time to go over points you want to spend more time on. Your doctor may ask:

  • When did you first notice your symptoms?
  • How have your symptoms changed over time?
  • Does anything seem to improve your symptoms?
  • Have you spent a lot of time in the sun, or have you used tanning beds?
  • Do you have a history of other skin conditions, such as skin cancer or psoriasis? What treatments have you received for those conditions?
  • Have you been diagnosed with any immune system disorders? If so, what treatments have you received?
  • Have you been diagnosed or treated for any other health conditions?
Dec. 06, 2022

Living with merkel cell carcinoma?

Connect with others like you for support and answers to your questions in the Neuroendocrine Tumors (NETs) support group on Mayo Clinic Connect, a patient community.

Neuroendocrine Tumors (NETs) Discussions

Anyone had surgery to remove typical carcinoids of the lung?

24 Replies Thu, Dec 07, 2023

Teresa, Volunteer Mentor
Learn About NETs and monthly meetings

81 Replies Wed, Dec 06, 2023

High or Fluctuating Chromogranin A Level: What does it mean?

155 Replies Sat, Dec 02, 2023

See more discussions
  1. Niederhuber JE, et al., eds. Nonmelanoma skin cancers. In: Abeloff's Clinical Oncology. 5th ed. Philadelphia, Pa.: Churchill Livingstone Elsevier; 2014. https://www.clinicalkey.com. Accessed Oct. 27, 2018.
  2. Merkel cell carcinoma. Plymouth Meeting, Pa.: National Comprehensive Cancer Network. https://www.nccn.org/professionals/physician_gls/default.aspx. Accessed Aug. 1, 2018.
  3. Merkel cell carcinoma treatment (PDQ): Patient version. National Cancer Institute. https://www.cancer.gov/types/skin/patient/merkel-cell-treatment-pdq#section/all. Accessed Oct. 27, 2018.
  4. Prevent skin cancer. American Academy of Dermatology. https://www.aad.org/spot-skin-cancer/learn-about-skin-cancer/prevent-skin-cancer. Accessed Oct. 27, 2018.
  5. Tai, P. Pathogenesis, clinical features, and diagnosis of Merkel cell (neuroendocrine) carcinoma. https://www.uptodate.com/contents/search. Accessed Oct. 27, 2018.
  6. Liu W, et al. Merkel cell polyomavirus infection and Merkel cell carcinoma. Current Opinion in Virology. 2016;20:20.