Prevalence of Differentiated High-Grade Thyroid Carcinoma Among Well-Differentiated Tumors: A Systematic Review and Meta-Analysis

Comparative analysis of follicular cell- derived thyroid carcinoma: assessing the impact of high-grade features in an advanced disease cohort

The 5th edition of the WHO Classification of Tumors of Endocrine Organs introduced the term Differentiated High-Grade Thyroid Carcinoma (DHGTC) to identify cases of differentiated follicular cell-derived thyroid carcinomas (DFCDTC) with a worse prognosis. This study aimed to determine the frequency and clinicopathological features of DHGTC within a cohort of advanced follicular cell-derived thyroid carcinomas (AdvTC) and compare them to non-high-grade DFCDTC (non-HGDTC) and poorly differentiated thyroid carcinoma (PDTC). A retrospective analysis was conducted on 138 patients with AdvTC who underwent total thyroidectomy followed by radioactive iodine therapy (131I). DHGTC was identified in 15.9% of the cases (22/138), showing a higher prevalence in this selected cohort of AdvTC compared to other studies. Compared to non-HGDTC, DHGTC was significantly associated with adverse clinicopathological features, including age ranges ≤ 18 and ≥ 55 years, presence of distant and synchronous metastasis, larger tumor size (> 2 cm), tall-cell subtype of papillary thyroid carcinoma, higher mitotic index (≥ 5/2 mm2), tumor necrosis, angioinvasion, higher AJCC 8th edition pT stage (pT3/T4), and more frequent administration of additional therapies, such as tyrosine kinase inhibitors. In comparison to PDTC, DHGTC displayed lower median tumor size, less frequent tumor necrosis, and a higher mitotic count. Independent prognostic factors for worse DSS in the entire cohort were age ≥ 55 years (HR = 19.625, p = 0.005) and male sex (HR = 7.441, p = 0.029). DHGTC cases consistently demonstrated worse clinical outcomes compared to non-HGDTC, including lower survival rates and higher persistence of disease at the end of follow-up. Our results validate the inclusion of DHGTC as a distinct high-grade subgroup within follicular cell-derived thyroid carcinomas, as proposed by the 5th WHO classification. DHGTC exhibits aggressive clinicopathological features and poor outcomes, supporting its relevance in clinical risk stratification and therapeutic decision-making.

Aggressive Types of Malignant Thyroid Neoplasms

Differentiated thyroid cancer (DTC) includes many subtypes, which demonstrate favorable to aggressive behavior. During the past decades, efforts have been made to describe aggressive thyroid cancers. Within DTC, aggressive variants constitute rare entities with unique histopathological features and compromised survival, as local and distant metastatic disease is frequent. In recent years, the distinct category of poorly differentiated thyroid cancer was introduced in 2004 and the type of differentiated high-grade thyroid carcinoma was recently added in the 2022 WHO classification of thyroid neoplasms. Finally, anaplastic thyroid cancer exhibits a rapid, resistant to therapy, progression and confers the shortest survival. In this review, we will present the characteristics of these thyroid cancer types and also discuss the treatment, management, and follow-up of these difficult cases. Emphasis was given to recent bibliography of the last decade.

Current evidences in poorly differentiated thyroid carcinoma: a systematic review and subsection meta-analysis for clinical decision making

BACKGROUND

Poorly differentiated thyroid carcinoma (PDTC) is a distinct entity with intermediate prognosis between indolent follicular thyroid cancers and anaplastic carcinoma. The management guidelines are not standardized for these cancers due its low prevalence and limited available literature. Therefore, we did this systematic review with emphasis on current evidence on diagnosis, imaging, molecular markers, and management of these carcinomas.

MATERIALS AND METHODS

We searched four databases, PubMed, Medline, EMBASE, and Emcare to identify studies published till October 2023. All studies reporting diagnostic tests, imaging, molecular marker expression and management of PDTC were included in the review. The meta-analysis was conducted on expression of molecular markers in these cancers following recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Random-effects meta-analysis was used to calculate pooled estimated prevalence with 95% confidence intervals. Based on the inclusion criteria, 62 articles were selected to be incorporated for the review. Differences in pathological diagnostic criteria of PDTC was noted in literature which was addressed in WHO 2022 diagnostic terminologies with expansion of the definition. Surgical management is uniformly recommended for early stage PDTC. However, literature is divided and anecdotal for recommendations on radioactive iodine (RAI), extent of neck dissection and adjuvant treatment in PDTC. Evidence for Next Generation Sequencing (NGS), novel theragnostic approaches, immunotherapy targets are evolving. Based on the subset analysis for expression of molecular markers, we found the most common markers expressed were TERT (41%), BRAF (28%) and P 53 (25%).

CONCLUSION

Poorly differentiated thyroid carcinomas have a high case fatality rate (up to 31%). Eighty-five % of the patients who succumb to the disease have distant metastasis. Even though under-represented in literature, evidence-based management of these aggressive tumors can help personalize the treatment for optimal outcomes.

A Comprehensive Review and Insights into the New Entity of Differentiated High-Grade Thyroid Carcinoma

Differentiated high-grade thyroid carcinoma (DHGTC) is a new subset within the spectrum of thyroid malignancies. This review aims to provide a comprehensive overview of DHGTC, focusing on its historical perspective, diagnosis, clinical characteristics, molecular profiles, management, and prognosis. DHGTC demonstrates an intermediate prognosis that falls between well-differentiated thyroid carcinoma and anaplastic thyroid carcinoma. Previously unenumerated, this entity is now recognized for its significant impact. Patients with DHGTC often present at an older age with advanced disease and exhibit aggressive clinical behavior. Molecularly, DHGTC shares similarities with other thyroid malignancies, harboring driver mutations such as BRAFV600E and RAS, along with additional late mutations. The unique behavior and histologic features of DHGTC underscore the necessity of precise classification for prognostication and treatment selection. This highlights the critical importance of accurate diagnosis and recognition by pathologists to enrich future research on this entity further.

Papillary thyroid carcinoma tall cell subtype (PTC-TC) and high-grade differentiated thyroid carcinoma tall cell phenotype (HGDTC-TC) have different clinical behaviour: a retrospective study of 1456 patients

AIMS

Papillary thyroid carcinoma, tall cell subtype (PTC-TC) is a potentially aggressive histotype. The latest World Health Organisation (WHO) classification introduced a novel class of tumours; namely, high-grade differentiated thyroid carcinoma (HGDTC), characterised by elevated mitotic count and/or necrosis, which can exhibit a tall cell phenotype (HGDTC-TC).

METHODS AND RESULTS

We analysed the clinical outcomes in a large retrospective cohort of 1456 consecutive thyroid carcinomas with a tall cell phenotype, including PTC-TC and HGDTC-TC. HGDTC-TC is uncommon, accounting for 5.3% (77 of 1379) of carcinomas with tall cell morphology. HGDTC-TC was associated with significantly older age, larger tumour size, angioinvasion, gross extrathyroidal extension, higher AJCC pT stage, positive resection margin and nodal metastasis (P < 0.05). Compared with PTC-TC, HGDTC was associated with a significantly decreased DSS, LRDFS and distant metastasis-free survival (DMFS; P < 0.001). The 10-year DSS was 72 and 99%, the 10-year LRDFS was 61 and 92% and the 10-year DMFS was 53 and 97%, respectively, for HGDTC-TC and PTC-TC. On multivariate analysis, the classification (HGDTC-TC versus PTC-TC) was an independent adverse prognostic factor for DSS, LRDF, and DMFS when adjusted for sex, age, angioinvasion, margin status, AJCC pT and pN stage.

CONCLUSIONS

Compared with PTC-TC, HGDTC-TC is associated with adverse clinicopathological features, a higher frequency of TERT promoter mutations (59% in HGDTC-TC versus 34% in PTC-TC) and incurs a significantly worse prognosis. HGDTC-TC is an independent prognostic factor for carcinoma with tall cell morphology. This validates the concept of HGDTC and the importance of tumour necrosis and high mitotic count for accurate diagnosis and prognosis of differentiated thyroid carcinomas.