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Update on eighth edition American Joint Committee on Cancer classification for Merkel cell carcinoma and histopathological parameters that determine prognosis
  1. Celestine M Trinidad1,2,
  2. Carlos A Torres-Cabala1,
  3. Victor G Prieto1,
  4. Phyu P Aung1
  1. 1 Department of Pathology, Dermatopathology Section, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
  2. 2 University of Santo Tomas Hospital Benavides Cancer Institute, Manila, Philippines
  1. Correspondence to Dr Phyu P Aung, Department of Pathology, Dermatopathology Section, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA; paung{at}


Merkel cell carcinoma (MCC) is a rare primary cutaneous neuroendocrine carcinoma. The annual incidence of MCC is increasing in the USA. Timely diagnosis and proper staging of this tumour are crucial as MCC has high rates of regional recurrence and lymph node and distant metastasis. In this review, we outline the key differences between the tumor node metastasis (TNM) staging criteria for MCC in the seventh and eighth editions of the AJCC Cancer Staging Manual. We also discuss histopathological parameters that are not included in the eighth edition of the manual but have been shown in other studies to predict a worse prognosis in patients with MCC. Correct assessment and reporting of these clinically relevant histopathological parameters is of utmost importance for practising pathologists as management differs according to the stage of the tumour. This review aims to increase awareness of all these parameters, and proper recognition would guide the treating clinicians towards the most appropriate treatment options that can be given to patients.

  • dermatopathology

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  • Handling editor Cheok Soon Lee.

  • Correction notice This article has been corrected since it was published Online First. An additional affiliation has been included for the first author.

  • Contributors PPA: idea and writing the manuscript. CMT: writing the draft manuscript. CAT and VGP reviewing the manuscript.

  • Funding PPA was supported by Institutional Start-up Funding from The University of Texas MD Anderson Cancer Center (MD Anderson).

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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