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Updated: Aug 5, 2026
13:45
Merkel Cell Polyomavirus Infection and Detection
Published on: February 7, 2019
Merkel cell carcinoma: an updated guide for pathologists
Paul W Harms1,2,3,4
1Department of Pathology, University of Michigan, Ann Arbor, Michigan, USA.
Histopathology
|August 3, 2026
Summary
Merkel cell carcinoma (MCC) diagnosis is challenging due to its aggressive nature and potential for misdiagnosis. This review highlights diagnostic pitfalls and recent advances, including new markers, to improve accuracy for this rare skin cancer.
Area of Science:
- Dermatopathology
- Oncology
- Diagnostic Pathology
Background:
- Merkel cell carcinoma (MCC) is an aggressive neuroendocrine skin cancer with increasing incidence.
- Prompt diagnosis is crucial due to high risks of recurrence, metastasis, and mortality.
- Accurate diagnosis can be difficult, especially with limited samples or unusual presentations.
Purpose of the Study:
- To review diagnostic challenges and nuances in Merkel cell carcinoma.
- To provide an updated differential diagnosis for MCC.
- To discuss the utility of traditional and novel diagnostic markers.
Main Methods:
- Review of literature on Merkel cell carcinoma diagnosis.
- Analysis of differential diagnostic considerations.
- Evaluation of immunohistochemical and molecular markers.
Main Results:
- MCC diagnosis can be confused with other small cell malignancies and cutaneous carcinomas.
- Immunohistochemical overlap exists with vulvar small cell carcinoma and WNT/Beta-catenin-activated nonpilomatrical carcinoma.
- New markers (SATB2, H3K27me3, POU4F3) and traditional markers (CK20, TTF1, neurofilament, Merkel cell polyomavirus) have specific utilities and caveats.
Conclusions:
- Accurate Merkel cell carcinoma diagnosis requires careful consideration of differential diagnoses and marker interpretation.
- Recent advances in markers and molecular analysis aid in achieving a more definitive diagnosis.
- Addressing diagnostic pitfalls is essential for timely management of this aggressive skin cancer.
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