Merkel Cell Carcinoma - Symptoms, Causes & Treatment
Medically reviewed by Dr. Anand S. Urhekar, MD, MD Pathology, Clinical Advisor · Last updated July 2026
A rare but aggressive neuroendocrine skin cancer that typically forms a firm, painless, rapidly growing red or violet nodule on sun-exposed skin of the head, neck or arms. It is strongly linked to Merkel cell polyomavirus, ultraviolet damage, older age and immunosuppression.
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Quick Answer
Merkel cell carcinoma is a rare, aggressive skin cancer that appears as a firm, painless, fast-growing red or purple nodule on sun-exposed skin, usually in people over 50. The AEIOU features are: Asymptomatic, Expanding rapidly, Immunosuppressed, Older than 50, and UV-exposed fair skin. It spreads early, so any nodule doubling in size within weeks needs urgent specialist referral.
Symptoms
- Firm, dome-shaped red, pink or violet nodule
- Painless despite rapid enlargement
- Shiny surface, sometimes with visible small blood vessels
- Most often on head, neck, eyelid or forearm
- May be accompanied by swollen local lymph nodes
Causes & Risk Factors
- Merkel cell polyomavirus (present in around 80% of cases)
- Chronic ultraviolet exposure
- Age over 50
- Immunosuppression (transplant, HIV, chronic lymphocytic leukaemia)
- Fair skin
Treatment & Management
- Urgent wide local excision
- Sentinel lymph node biopsy — routine because of early spread
- Adjuvant radiotherapy to the primary site and nodal basin
- Immune checkpoint inhibitors (avelumab, pembrolizumab) for advanced disease
- Close surveillance, as recurrence risk is high in the first two years
When to See a Doctor
Seek urgent medical review for any firm, painless nodule that has clearly grown within the past few weeks, especially if you are over 50, fair-skinned or immunosuppressed.
Frequently Asked Questions
How fast does Merkel cell carcinoma grow?
Very fast — many patients report a lesion that appeared and doubled in size within a few weeks. Rapid growth without pain is the single most important warning feature.
Is it more dangerous than melanoma?
Merkel cell carcinoma has a higher case-fatality rate than melanoma, though it is far rarer. Early detection and treatment substantially improve outcomes.
Does it look like a cyst or boil?
Often yes, which delays diagnosis. Unlike a boil it is painless and does not resolve or discharge; unlike a cyst it grows relentlessly.
Related Conditions
Medical References
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Medical Disclaimer: This information is for educational purposes only and is not intended as medical advice. The content on this page should not be used to diagnose or treat any health problem. Always consult with a qualified healthcare professional for proper medical evaluation, diagnosis, and treatment of your condition.