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PubMed This is a summary of 18 peer-reviewed journal articles Updated
Oncology · Merkel cell carcinoma

Starting Your Journey: Understanding Merkel Cell Carcinoma

At a Glance

Merkel cell carcinoma (MCC) is a rare, aggressive skin cancer, but modern immunotherapy treatments have dramatically improved outcomes. Prompt evaluation by a multidisciplinary team and a sentinel lymph node biopsy are critical first steps in staging and treating the disease.

If you have just been diagnosed with Merkel cell carcinoma (MCC), it is completely normal to feel overwhelmed. MCC is a rare and aggressive form of skin cancer that develops at the base of the outermost layer of the skin (the epidermis), often appearing as a firm, painless, flesh-colored or bluish-red nodule [1][2]. While it is more rare than melanoma, it grows more quickly and requires prompt, specialized care [3][4].

The landscape of MCC treatment has changed dramatically in recent years. What was once a very difficult diagnosis to manage has been transformed by breakthroughs in immunotherapy—treatments that help your own immune system find and destroy cancer cells [5][6].

Three Stabilizing Facts

In the first few days after a diagnosis, it is easy to focus on the “rare and aggressive” labels. However, three key facts can help anchor your perspective:

  1. Immunotherapy is a Game-Changer: Modern treatments like checkpoint inhibitors (e.g., avelumab and pembrolizumab) have revolutionized care, often providing long-term, durable responses even in advanced cases [5][7].
  2. Detection is Improving: While the number of cases is rising—with approximately 0.7 cases per 100,000 people in the U.S.—doctors are now better at identifying it early, which significantly improves the chances of successful treatment [4][8].
  3. Specialized Care Works: Patients who receive care from a multidisciplinary team (a group of experts including surgeons, radiation oncologists, and dermatologists) at experienced medical centers typically have much better outcomes [9][10].

Understanding the Two Types of MCC

Researchers have discovered that MCC generally follows one of two biological paths. Knowing which one you have can help your doctor tailor your care.

Feature Virus-Positive (MCPyV+) UV-Induced (Virus-Negative)
Primary Cause Merkel Cell Polyomavirus, a common virus that usually lives harmlessly on the skin but can occasionally trigger cancer [11][12]. Ultraviolet (UV) Radiation from long-term sun exposure or tanning beds, which causes genetic damage to skin cells [13][14].
Biology The virus “hides” inside the cell’s DNA, causing it to grow uncontrollably [13]. The tumor has a very high mutation burden (many genetic “typos”) caused by sun damage [13][15].
Prognosis Generally associated with a slightly more favorable outlook [11][16]. Can be more complex to treat, though it often responds well to immunotherapy [11][16].

Your Path Forward

Because MCC is rare, the most important next step is ensuring your care is managed by a team that sees this disease frequently [9]. Your doctors will likely perform a sentinel lymph node biopsy (SLNB), a procedure to check if the cancer has spread to nearby lymph nodes, which is the most accurate way to “stage” the disease and determine your treatment plan [17][18].

While the diagnosis is serious, you are entering treatment at a time when medical science has more effective tools to fight this disease than ever before [5][6].

Common questions in this guide

What does a Merkel cell carcinoma tumor look like?
Merkel cell carcinoma often appears as a firm, painless, flesh-colored or bluish-red nodule on the skin. It tends to grow very quickly, so any rapid changes in a skin growth should be evaluated promptly by a doctor.
What is the difference between virus-positive and UV-induced Merkel cell carcinoma?
Virus-positive MCC is triggered by the Merkel cell polyomavirus, which causes the cancer cells to grow uncontrollably. UV-induced MCC is caused by genetic damage from long-term sun exposure or tanning beds. Knowing which type you have helps your doctor tailor your treatment.
Why do I need a sentinel lymph node biopsy for MCC?
A sentinel lymph node biopsy is a procedure that checks if the cancer has spread from the skin to your nearby lymph nodes. This is the most accurate way to stage the disease and helps your medical team determine the most effective treatment plan for you.
Can immunotherapy be used to treat Merkel cell carcinoma?
Yes, immunotherapy has revolutionized the treatment of Merkel cell carcinoma. Medications known as checkpoint inhibitors, such as avelumab and pembrolizumab, help your own immune system find and destroy cancer cells, often providing long-term benefits even in advanced cases.
Does my sun exposure history increase my risk for Merkel cell carcinoma?
Long-term sun exposure and tanning bed use are significant risk factors for developing the UV-induced type of Merkel cell carcinoma. Ultraviolet radiation causes genetic damage to skin cells, which can trigger this aggressive form of skin cancer.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Has my tumor been tested for the Merkel cell polyomavirus (MCPyV)?
  2. 2.What was the result of my sentinel lymph node biopsy, and how does it affect my stage?
  3. 3.How much experience does this medical center have in treating Merkel cell carcinoma specifically?
  4. 4.Is immunotherapy, like avelumab or pembrolizumab, an option for me now or in the future?
  5. 5.Does my personal medical history, such as my age or any other health conditions, affect my risk of the cancer returning?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (18)
  1. 1

    The Role of the Large T Antigen in the Molecular Pathogenesis of Merkel Cell Carcinoma.

    Myrda J, Bremm F, Schaft N, Dörrie J

    Genes 2024; (15(9)) doi:10.3390/genes15091127.

    PMID: 39336718
  2. 2

    Merkel cell carcinoma incidence is increasing in Sweden.

    Zaar O, Gillstedt M, Lindelöf B, et al.

    Journal of the European Academy of Dermatology and Venereology : JEADV 2016; (30(10)):1708-1713 doi:10.1111/jdv.13698.

    PMID: 27136306
  3. 3

    Merkel cell carcinoma with seborrheic keratosis: A unique association.

    Anand MS, Krishnamurthy S, Ravindranath S, Ranganathan J

    Indian journal of pathology & microbiology 2018; (61(1)):101-102 doi:10.4103/IJPM.IJPM_659_16.

    PMID: 29567894
  4. 4

    Assessment of Age, Period, and Birth Cohort Effects and Trends in Merkel Cell Carcinoma Incidence in the United States.

    Jacobs D, Huang H, Olino K, et al.

    JAMA dermatology 2021; (157(1)):59-65 doi:10.1001/jamadermatol.2020.4102.

    PMID: 33146688
  5. 5

    Merkel Cell Carcinoma.

    Lewis DJ, Sobanko JF, Etzkorn JR, et al.

    Dermatologic clinics 2023; (41(1)):101-115 doi:10.1016/j.det.2022.07.015.

    PMID: 36410971
  6. 6

    Immune Checkpoint Inhibitors in Merkel Cell Carcinoma of the Skin: A 2025 Comprehensive Review.

    Tai P, Alqaisi O, Al-Ghabeesh S, et al.

    Cancers 2025; (17(19)) doi:10.3390/cancers17193272.

    PMID: 41097798
  7. 7

    Merkel cell carcinoma: a review of clinical management with focus on Asian patients.

    Nakano E, Ogata D, Namikawa K, Yamazaki N

    Japanese journal of clinical oncology 2023; (53(8)):673-679 doi:10.1093/jjco/hyad059.

    PMID: 37288476
  8. 8

    International Increases in Merkel Cell Carcinoma Incidence Rates between 1997 and 2016.

    Olsen CM, Pandeya N, Whiteman DC

    The Journal of investigative dermatology 2021; (141(11)):2596-2601.e1 doi:10.1016/j.jid.2021.04.007.

    PMID: 33932460
  9. 9

    Patient Characteristics and Outcomes in Clinically Misdiagnosed Patients With Merkel Cell Carcinoma.

    Li Y, Tran T, Lee BA, et al.

    The Journal of surgical research 2025; (309()):71-79 doi:10.1016/j.jss.2025.03.005.

    PMID: 40220478
  10. 10

    Merkel Cell Carcinoma: New Trends.

    Zwijnenburg EM, Lubeek SFK, Werner JEM, et al.

    Cancers 2021; (13(7)) doi:10.3390/cancers13071614.

    PMID: 33807446
  11. 11

    Diagnosis and treatment of Merkel cell carcinoma: European consensus-based interdisciplinary guideline - Update 2022.

    Gauci ML, Aristei C, Becker JC, et al.

    European journal of cancer (Oxford, England : 1990) 2022; (171()):203-231 doi:10.1016/j.ejca.2022.03.043.

    PMID: 35732101
  12. 12

    Merkel Cell Polyomavirus Exhibits Dominant Control of the Tumor Genome and Transcriptome in Virus-Associated Merkel Cell Carcinoma.

    Starrett GJ, Marcelus C, Cantalupo PG, et al.

    mBio 2017; (8(1)) doi:10.1128/mBio.02079-16.

    PMID: 28049147
  13. 13

    Structure of Merkel Cell Polyomavirus Capsid and Interaction with Its Glycosaminoglycan Attachment Receptor.

    Bayer NJ, Januliene D, Zocher G, et al.

    Journal of virology 2020; (94(20)) doi:10.1128/JVI.01664-19.

    PMID: 32699083
  14. 14

    Expression of Genes Associated With Epithelial-Mesenchymal Transition in Merkel Cell Polyomavirus-Negative Merkel Cell Carcinoma.

    Karpinski P, Rosales I, Laczmanski L, et al.

    Laboratory investigation; a journal of technical methods and pathology 2023; (103(8)):100177 doi:10.1016/j.labinv.2023.100177.

    PMID: 37207705
  15. 15

    Modern diagnostics and treatment of Merkel cell carcinoma.

    Weilandt J, Peitsch WK

    Journal der Deutschen Dermatologischen Gesellschaft = Journal of the German Society of Dermatology : JDDG 2023; (21(12)):1524-1546 doi:10.1111/ddg.15214.

    PMID: 37875785
  16. 16

    Morphologic and immunophenotypical features distinguishing Merkel cell polyomavirus-positive and negative Merkel cell carcinoma.

    Kervarrec T, Tallet A, Miquelestorena-Standley E, et al.

    Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc 2019; (32(11)):1605-1616 doi:10.1038/s41379-019-0288-7.

    PMID: 31201352
  17. 17

    Updates on Merkel Cell Carcinoma.

    Emge DA, Cardones AR

    Dermatologic clinics 2019; (37(4)):489-503 doi:10.1016/j.det.2019.06.002.

    PMID: 31466589
  18. 18

    Treatment of primary Merkel cell carcinoma: Radiotherapy can be an effective, less morbid alternative to surgery.

    Hong AM, Stretch JR, Thompson JF

    European journal of surgical oncology : the journal of the European Society of Surgical Oncology and the British Association of Surgical Oncology 2021; (47(2)):483-485 doi:10.1016/j.ejso.2020.05.013.

    PMID: 32736916

This page provides general information about a new Merkel cell carcinoma diagnosis. Always consult with your multidisciplinary oncology team for personalized staging and treatment recommendations.

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