[Thyroid carcinoma--differentiated, poorly differentiated and anaplastic carcinoma]

Area of Science:

• Endocrinology
• Pathology
• Oncology

Context:

• The classification of thyroid carcinomas has evolved.
• The 2004 World Health Organization (WHO) edition introduced poorly differentiated carcinoma as a distinct entity.
• Histological criteria for this diagnosis were revised.

Purpose:

• To detail the revised histological criteria for poorly differentiated thyroid carcinoma.
• To analyze the impact of the new classification on the incidence and prognosis of this thyroid cancer.
• To compare the outcomes under the new WHO definition versus previous classifications.

Summary:

• Poorly differentiated thyroid carcinoma was newly defined in the 2004 WHO classification.
• Revised criteria include necrosis and increased mitoses, alongside Sakamoto's original solid, trabecular, and schirrhous growth patterns.
• This revised definition impacts the carcinoma's incidence (1-5% of thyroid malignancies) and indicates a more aggressive outcome.

Impact:

• The 2004 WHO classification significantly altered the understanding of poorly differentiated thyroid carcinoma's incidence.
• The revised criteria highlight a more aggressive clinical behavior compared to previous definitions.
• This reclassification is crucial for accurate diagnosis, treatment planning, and prognostic assessment of thyroid cancer.