Carcinomas of the Thyroid

3rd edition – November 2025

Updated following the publication of the 2025 World Health Organization (WHO) Classification of Endocrine and Neuroendocrine Tumours, 5th edition.

SUMMARY OF CHANGES

• Updated to Union for International Cancer Control TNM9 staging, including errata published October 2025.
• Revised guide to harmonise with ICCR style for element titles and value list.
• Revised scope for clarity and to harmonise with ICCR style.
• Updated the ‘Clinical information’ element.
• Updated the ‘Operative findings’ element.
• Added a new non-core element ‘Block identification key’.
• Updated the ‘Histological tumour type’ element to the 5th edition WHO Classification of Endocrine and Neuroendocrine Tumours.
• Renamed the ‘Mitotic activity’ element to ‘Mitotic count’ and updated.
• Removed the element ‘Histological tumour grade’.
• Renamed the ‘Necrosis’ element ‘Tumour necrosis’.
• Renamed the ‘Lymphatic or blood vessel invasion’ element to make two new elements ‘Lymphatic invasion’ and ‘Vascular invasion’.
• Updated the ‘Margin status’ element.
• Removed the element ‘C-cell hyperplasia’.
• Updated the ‘Coexistent pathology’ element.
• ‘Ancillary studies’ was changed to a core element and expanded. ‘Representative blocks for ancillary studies’ was added as non-core.
• Other minor updates to elements were also included.
• Revised all notes, including incorporation of the 5th edition WHO Classification of Endocrine and Neuroendocrine Tumours.

• To reference this dataset please use the following citation: Ghossein R, Abrosimov AY, Al Ghuzlan A, Barletta J, Fuchs TL, Kondo T, Mete O, Moonim MT, Poller DN, Tallini G, Tuttle RM, Viswanathan K, Xu B, Lax SF, Gill AJ (2025). Carcinoma of the thyroid Histopathology Reporting Guide. 3rd edition. International Collaboration on Cancer Reporting; Sydney, Australia. ISBN: 978-1-922324-71-9.

2nd edition – June 2020

Updated following revision of Lymphovascular invasion.

• To reference this dataset please use the following citation: Ghossein R, Barletta J, Bullock M, Johnson S, Kakudo K, Lam A, Moonim MT, Poller D, Tallini G, Tuttle RM, Xu B, Gill A (2020). Carcinoma of the Thyroid Histopathology Reporting Guide. 2nd edition. International Collaboration on Cancer Reporting; Sydney, Australia. ISBN: 978-1-922324-08-5.

• Read more on the Carcinoma of the thyroid dataset from the journal article written by the dataset authors: Data set for reporting carcinoma of the thyroid: recommendations from the International Collaboration on Cancer Reporting. Ghossein R, Barletta JA, Bullock M, Johnson SJ, Kakudo K, Lam AK, Moonim MT, Poller DN, Tallini G, Tuttle RM, Xu B, Gill AJ. Hum Pathol. 2021 Apr;110:62-72. doi: 10.1016/j.humpath.2020.08.009. Epub 2020 Sep 10.

The 3rd edition of the dataset for Carcinoma of the thyroid was developed by the following international team:

• Chair – Ronald Ghossein, USA
• Series Champion – Anthony Gill, Australia
• ICCR representative – Sigurd Lax, Austria

Domain experts:

• Alexander Abrosimov, Russia
• Abir Al Ghuzlan, France
• Justine Barletta, USA
• Talia Fuchs, Australia
• Tetsuo Kondo, Japan
• Ozgur Mete, Canada
• Mufaddal Moonim, UK
• David Poller, UK
• Giovanni Tallini, Italy
• Robert Michael Tuttle, USA
• Kartik Viswanathan, USA
• Bin Xu, USA

Authors of the previous editions of this dataset are available here.