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Merkel cell carcinoma

Last reviewed: 5 Oct 2024
Last updated: 20 Sep 2024

Summary

Definition

History and exam

Key diagnostic factors

  • firm, nontender, red or pink-to-violaceous or skin-colored papule or subcutaneous nodule
  • rapidly growing lesion
Full details

Other diagnostic factors

  • enlarged lymph nodes
  • ulceration or bleeding cutaneous lesion
  • small papules or nodules surrounding a primary lesion
Full details

Risk factors

  • cumulative ultraviolet (UV) exposure
  • immunosuppression
  • advancing age
  • male sex
  • white skin
  • Merkel cell polyomavirus (MCPyV) infection with oncogenic transformation
Full details

Diagnostic tests

1st tests to order

  • biopsy and histopathologic assessment
  • dermoscopy
Full details

Tests to consider

  • lymph node ultrasound
  • whole-body PET scan
  • CT scan with contrast chest/abdomen/pelvis (± neck)
  • brain MRI
  • fine-needle aspiration or core biopsy
  • sentinel lymph node biopsy (SLNB)
  • Merkel cell polyomavirus serology
Full details

Emerging tests

  • circulating tumor DNA (ctDNA) analysis

Treatment algorithm

ACUTE

localized disease: stage I or II (T-any cN0 M0)

regional disease: stage IIIA

regional disease: unknown primary tumor with clinically apparent nodal disease

regional disease: stage IIIB

distant metastatic disease: stage IV

Contributors

Authors

Kelly Harms, MD, PhD

Associate Professor of Dermatology

Michigan Medicine

University of Michigan

Ann Arbor

MI

Disclosures

KH is a panel member for NCCN guidelines on Merkel cell carcinoma. She serves as Chair of Professionalism and Ethics for the Michigan Dermatological Society Board of Directors. KH is married to Paul Harms, a co-author of research on Merkel cell carcinoma.

Alison Lee, MD, MHS

Clinical Fellow

Department of Dermatology

Michigan Medicine

University of Michigan

Ann Arbor

MI

Disclosures

AL declares that she has no competing interests.

Peer reviewers

Isaac Brownell, MD, PhD

Senior Investigator

Dermatology Branch

National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)

National Institutes of Health (NIH)

Bethesda

MD

Disclosures

IB declares that he has no competing interests.

Zoe Venables, MbChB, MMedSci, MRCP

Clinical Associate Professor and Consultant Dermatologist

Norfolk and Norwich University Hospitals NHS Foundation Trust

Norwich

UK

Disclosures

ZV declares that she has no competing interests.

  • Merkel cell carcinoma images
  • Differentials

    • Basal cell carcinoma (BCC)
    • Squamous cell carcinoma (SCC) of the skin
    • Amelanotic/hypomelanotic melanoma
    More Differentials
  • Guidelines

    • NCCN clinical practice guidelines in oncology: Merkel cell carcinoma
    • Merkel-cell carcinoma: ESMO-EURACAN clinical practice guideline for diagnosis, treatment and follow-up
    More Guidelines
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