Endocrine and Neuroendocrine Tumors: Updates From the 5th Edition of the World Health Organization "Blue Book"

Area of Science:

• Endocrinology
• Oncology
• Pathology

Background:

• The World Health Organization (WHO) Classification of Tumours series is a key resource for tumor classification.
• The 5th edition of the Endocrine and Neuroendocrine Tumours Blue Book was digitally released in 2022.

Purpose of the Study:

• To summarize the key changes in the 5th edition of the WHO Classification of Endocrine and Neuroendocrine Tumours.
• To highlight updated diagnostic criteria and terminology compared to the 2017 edition.

Main Methods:

• Comparative analysis of the 2017 and 2022 WHO classifications for endocrine and neuroendocrine tumors.
• Review of updated diagnostic criteria, terminology, and classification schemes.

Main Results:

• Refined understanding of neuroendocrine cell relationships and a cytogenesis-based classification for pituitary neuroendocrine tumors.
• Reclassification of thyroid neoplasms based on cytogenesis and pathogenesis, with new terminology for benign endocrine proliferations.
• Updated classification of parathyroid disease and introduction of new terminologies like thyroid follicular nodular disease and adrenocortical nodular disease.

Conclusions:

• The 5th edition advances endocrine tumor knowledge with molecular information and refined diagnostic standards.
• Accurate immunohistochemistry and quantification of cellular proliferation are critical for diagnosis.
• The classification incorporates genetic tumor syndromes and essential technical considerations for endocrine pathology.