Disease Directory Merkel Cell Carcinoma
Oncology

Merkel Cell Carcinoma

Also known as: MCC, Merkel cell polyomavirus carcinoma, trabecular carcinoma of the skin

Prevalence

0.6–0.7 in 100,000 (USA); rising incidence

Onset

Elderly (median age 75); immunosuppressed patients may present younger

Type

Sporadic; risk markedly elevated in immunosuppression

Gene

MCPyV (viral), RB1, TP53

About Merkel Cell Carcinoma

Merkel cell carcinoma is a rare but highly aggressive primary cutaneous neuroendocrine carcinoma with two distinct molecular aetiologies: integration of Merkel cell polyomavirus (MCPyV) DNA into the host genome, accounting for approximately 80% of cases in immunocompetent patients in low-UV climates, and UV-induced somatic mutational burden in virus-negative tumours. MCC carries a disease-specific mortality of approximately 33% and a high propensity for regional lymph node and distant metastasis; however, the tumour is exquisitely immunogenic, making it one of the most responsive solid tumours to immune checkpoint inhibitors. Immunosuppression — whether from organ transplant, HIV, or haematological malignancy — dramatically increases incidence and worsens outcomes.

Common Clinical Features

Rapidly growing, firm, flesh-coloured or violaceous, shiny nodule on sun-exposed skin of the head, neck, or extremities Regional lymphadenopathy at presentation in 20–30% of patients Ulceration of the primary tumour in advanced or neglected lesions Distant metastases to liver, lung, bone, and brain in stage IV disease Cutaneous satellite or in-transit metastases between the primary site and draining lymph node basin Paraneoplastic autoimmune encephalitis (anti-Ma, anti-amphiphysin antibodies) in rare cases Rapid recurrence at or near the primary site after excision, particularly in virus-negative tumours

Clinical Trial Eligibility Tips

What to know before applying to Merkel Cell Carcinoma trials.

MCPyV serology (Merkel cell polyomavirus antibody titre) and tumour MCPyV status by IHC or PCR are increasingly used as eligibility or stratification factors — obtain this data from the pathology report or arrange testing.

Immunosuppression management is critical: transplant patients may need immunosuppression reduction before or during checkpoint inhibitor trials, requiring co-ordination with transplant medicine.

PD-L1 expression testing and tumour mutational burden (TMB) may be required for some checkpoint inhibitor combination trials; ensure comprehensive molecular profiling is available.

Patient Resources

Patient Organization

Skin Cancer Foundation

Visit website ↗

Natural History Registry

Cancer Registry of Norway / SEER (USA)

Join registry ↗

Orphanet

European reference resource for rare diseases (ORPHA:49643)

View on Orphanet ↗

NORD

National Organization for Rare Disorders

Search NORD ↗

Find recruiting Merkel Cell Carcinoma trials

Search 500,000+ studies from ClinicalTrials.gov, filtered for Merkel Cell Carcinoma. Updated daily.

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