Re-Analyzing Differentiated High-Grade Thyroid Carcinoma and Elevated Ki-67 Proliferation: A Single-Center...

Area of Science:

• Endocrinology
• Oncology
• Pathology

Background:

• The 2022 WHO classification introduced differentiated high-grade thyroid carcinoma (DHGTC), a distinct entity with high-grade features despite maintained differentiation.
• DHGTC presents unique challenges in risk stratification and treatment planning.

Purpose of the Study:

• To evaluate the clinical characteristics of DHGTC.
• To assess treatment responses in DHGTC patients.
• To determine the prognostic impact of the Ki-67 proliferation index in DHGTC.

Main Methods:

• Retrospective review of 3100 differentiated thyroid carcinoma (DTC) patients (2017-2024).
• Identification and re-classification of 56 DHGTC cases based on mitotic count and/or tumor necrosis.
• Analysis of 69 DTC patients with elevated Ki-67 (>5%) for clinical significance.

Main Results:

• DHGTC cases frequently exhibited tumor necrosis (87.5%) and high mitotic activity (19.6%).
• All DHGTC patients were high-risk (2025 ATA guidelines), with 42.8% showing incomplete treatment response and 28.6% needing salvage interventions.
• Elevated Ki-67 (≥15%) correlated with poorer outcomes in general DTC but showed limited prognostic value within the DHGTC subset.

Conclusions:

• DHGTC is associated with aggressive histopathology and a high risk of persistent or recurrent disease.
• An elevated Ki-67 index (≥15%) is an adverse marker in general DTC but its prognostic utility in DHGTC is inconclusive due to small sample sizes.