Follicular thyroid carcinoma (FTC) is the second most common type of thyroid cancer, presenting unique diagnostic and therapeutic challenges. This review provides a comprehensive analysis of the recent advancements in the diagnosis and treatment of FTC, emphasizing the significance of these developments in improving patient outcomes. We discuss the evolution of diagnostic techniques, including advancements in imaging modalities, fine needle aspiration biopsy, and molecular diagnostics, which have enhanced the accuracy of FTC detection and differentiation from benign conditions. The review also evaluates current treatment strategies, including surgical interventions, radioactive iodine therapy, and targeted therapies, examining their effectiveness and impact on patient prognosis. Additionally, we address ongoing challenges in FTC management, such as variability in treatment guidelines and disparities in care. Finally, the review explores emerging therapies and future research directions, highlighting innovations that may further optimize FTC management. By synthesizing current knowledge and identifying future research opportunities, this review aims to contribute to refining diagnostic and therapeutic approaches for FTC.

BACKGROUND: The 2022 WHO Classification categorizes oncocytic (OTC) and follicular thyroid carcinoma (FTC) based on the degree of capsular and vascular invasion into minimally invasive (MI), encapsulated angioinvasive (EA) and widely invasive tumors (WI). While associations with clinical outcomes have been studied extensively in FTC, robust clinical data are lacking for OTC. We aimed to investigate the impact of the reclassification of OTC and FTC by the 2022 WHO Classification on clinical outcomes.
METHODS: All adult OTC and FTC patients treated at the Erasmus MC (the Netherlands) between 2000 and 2016 were retrospectively included. All tumors were extensively revised by two independent pathologists, facilitated by Palga: Dutch Pathology Databank. Kaplan-Meier curves were used to study the association of the 2004 and 2022 WHO Classification with overall survival (OS), disease-specific survival (DSS), recurrence-free survival (RFS) and radioactive iodine (RAI) refractory disease.
RESULTS: Fifty-two OTC and 89 FTC patients were included, of which 15 (28.8%) OTC and 34 (38.2%) FTC tumors were reclassified as EAOTC or EAFTC. The 2022 WHO Classification substantially improved risk stratification in both subtypes for DSS, compared with the 2004 edition. Ten-year DSS rates were 100% for MIOTC, 92.9% for EAOTC and 56.5% for WIOTC, compared to 100% (MIOTC) and 64.2% (WIOTC) following the 2004 WHO Classification. For FTC and RAI-refractory disease, similar trends were observed.
CONCLUSIONS: Classification of OTC and FTC into three subcategories as defined by the 2022 WHO Classification substantially improves discrimination between low, intermediate and high risk patients, especially for DSS and RAI-refractory disease.

BACKGROUND: Follicular thyroid carcinoma (FTC), the second most prevalent thyroid cancer after papillary thyroid cancer (PTC), tends to metastasize distantly, leading to poorer outcomes. Despite substantial research, a holistic bibliometric analysis of FTC literature is lacking. This study aims to fill this gap by employing bibliometric methods to track FTC research evolution.
METHODS: English FTC publications were systematically gathered from the Web of Science. Bibliometric analysis, using R, VOSviewer, CiteSpace, and Excel, synthesized data and explored global research trends and topics.
RESULTS: From 2000 to 2023, 9086 authors from 1953 institutions across 75 countries contributed to 1776 papers in 491 academic journals on FTC. The last two decades have witnessed a steady increase in publications related to FTC, with the United States leading in terms of publication volume. The United States dominated both in publications and citations, with the National Cancer Institute and Sheue-Yann Cheng as leading contributors. The journal \'Thyroid\' featured the most publications, while the \'Journal of Clinical Endocrinology and Metabolism\' ranked highest in citation frequency. Research focused on gene expression analysis and preoperative diagnostics, with recent trends shifting toward prognosis management and machine learning due to advances in medical technology and increased health awareness.
CONCLUSIONS: This comprehensive bibliometric analysis has mapped the landscape of FTC research, highlighting key contributors, institutions, and thematic trends. Current discourse predominantly revolves around genetic analysis, prognostic determinants, and preoperative diagnostics in FTC. This foundational work guides future FTC research, providing insights into its evolution.

Objective Differentiated thyroid cancer (DTC) is rare in the pediatric population, with most data from the Western world. We aimed to describe the clinical presentation, treatment intervention, histopathological characteristics, complications, follow-up, and response to treatment in 17 patients with DTC at or below the age of 20 years. Interventions This was a retrospective cohort study at King Abdulaziz Medical City, Jeddah, Saudi Arabia. We included patients aged younger than 20 years with DTC. Total or near-total thyroidectomy was performed in 82% of the patients, central and/or lateral neck dissection in 35% of cases, and radioactive iodine (RAI) ablation in 76% of cases. Results The study included 17 patients (14 females), with a median age of 16 years at the time of diagnosis. Thyroid nodules were the main complaint in 88% of the patients. Thyroid ultrasonography was the main method for the initial evaluation. Papillary cancer was the most common type of tumor, and lymph node spread was found in 82% of the patients. Moreover, 40% of the patients exhibited excellent responses to therapy, with 35% showing indeterminate results. Only 23.5% of the patients developed hypocalcemia postoperatively. Conclusions Classical papillary thyroid carcinoma was the predominant histopathological type, and most patients showed excellent responses to therapy, followed by indeterminate in most of the cases. The most common presentation was a neck nodule, signifying the role of thorough physical neck examinations. Finally, recurrence occurred in a minority of patients. However, none of these patients died.

A 71-year-old woman was diagnosed with unresectable metastatic follicular thyroid carcinoma (FTC) and thyrotoxicosis. She was negative for the presence of thyroxine receptor antibody and thyroid-stimulating antibody. Whole-body scintigraphy revealed increased 99mTc-pertechnetate uptake in metastatic bone lesions but not in the thyroid nodule. Since radioactive iodine therapy was not applicable because the canalis vertebralis had been invaded, treatment with lenvatinib was initiated, along with methimazole and potassium iodide. The serum level of thyroid hormone decreased. The patient developed hypothyroidism, which continued after the methimazole was stopped, suggesting that lenvatinib suppressed the hyperthyroidism. To our best knowledge, this is the first report of a patient with functioning bone lesions of metastatic FTC in whom hyperthyroidism was controlled by lenvatinib without radioactive iodine therapy.

UNASSIGNED: Struma ovarii is a highly specialized teratoma consisting primarily of mature thyroid tissue. However, malignant struma ovarii coexisting with thyroid carcinoma, not to mention autoimmune disease, is uncommon. Malignant struma ovarii complicated with papillary thyroid carcinoma, Hashimoto\'s thyroiditis and polycystic ovarian syndrome has never been reported in literature.
UNASSIGNED: A 32-year-old female was admitted to our hospital due to a history of abdominal distension and menolipsis over the past half a year. Physical examination touched a 6 × 6 cm mass with a clear boundary, normal movement, and no pressing pain in the right adnexal area, Imaging revealed a cystic solid mass of 6 × 7 cm in the right ovary and the level of tumor markers including CA125, CA199, CA153, CEA, AFP were normal, but with low TSH and increased TPOAb, TGAb, TRAb. Laparoscopic right ovary tumor resection was performed, followed by comprehensive staging surgery, as well as thyroidectomy after pathologic diagnosis. The patient was diagnosed with a combination of follicular thyroid cancer from struma ovarii, papillary thyroid carcinoma and Hashimoto\'s thyroiditis, along with polycystic ovarian syndrome. Immunohistochemical staining showed positivity for Ag, CK-pan, CK7, PAX8 and TTF-1 in the right ovarian mass, and the left thyroid was positive for the BRAF V600E mutation.
UNASSIGNED: The patient underwent thyroxine suppression therapy and radioactive iodine 131I therapy after operation. Serum thyroglobulin was undetectable, and no signs of recurrence or metastasis were detected in the imaging examination at the 2-year follow-up.
UNASSIGNED: Malignant struma ovarii coexisting with thyroid carcinoma is rare. No report has been identified in literature review on the rare malignant struma ovarii coexisting with thyroid carcinoma, Hashimoto\'s thyroiditis and polycystic ovarian syndrome. Our case can offer experience of diagnosis and treatment to some extent for such rare case. Therefore, it is essential to consider the association between ovarian tumors and the endocrine system. This case is valuable in understanding the diagnosis and management of such an unusual complicated disease.

Telomerase reverse transcriptase (TERT) promoter mutations are associated with tumor aggressiveness. This study aimed to demonstrate the ultrasonographic (US) features of TERT promoter-mutated follicular thyroid cancer (FTC) and evaluate their predictive performance. A total of 63 patients with surgically confirmed FTC between August 1995 and April 2021 were included. All data were available for analysis of preoperative US findings and TERT promoter mutation results. Genomic DNA was extracted from the archived surgical specimens to identify TERT promoter mutations. Logistic regression analysis was performed to compare US findings between TERT promoter-mutated and wild-type FTCs. Of the 63 patients with FTC, 10 (15.9%) had TERT promoter mutations. TERT promoter-mutated FTCs demonstrated significantly different US suspicion categories compared to wild-type FTCs (Ps = 0.0054 for K-TIRADS and 0.0208 for ACR-TIRADS), with a trend toward an increasing prevalence of the high suspicion category (40.0% for both K-TIRADS and ACR-TIRADS; Ps for trend = 0.0030 for K-TIRADS and 0.0032 for ACR-TIRADS). Microlobulated margins and punctate echogenic foci were independent risk factors associated with TERT promoter mutation in FTC (odds ratio = 9.693, 95% confidence interval = 1.666-56.401, p = 0.0115 for margins; odds ratio = 8.033, 95% confidence interval = 1.424-45.309, p = 0.0182 for punctate echogenic foci). There were no significant differences in the composition and echogenicity of the TERT promoter-mutated and wild-type FTCs. TERT promoter-mutated FTCs were categorized more frequently as high suspicion by the K-TIRADS and ACR-TIRADS. Based on US findings, the independent risk factors for TERT promoter mutations in FTC are microlobulated margins and punctate echogenic foci.

Subcutaneous implantation is an unexpected complication of thyroid surgery. Our study aimed to analyze the clinical features and outcomes of implantation after thyroid surgery. We retrospectively searched for the patients with implants of thyroid tumor after surgery from our database prior to August 2023. The clinical and pathological data were reviewed. Six female patients with a mean age of 33.6 ± 13.3 years were enrolled in this study. There was a rare case with mucinous adenocarcinoma, three follicular thyroid carcinoma, and two papillary thyroid carcinoma. The case with primary enteric adenocarcinoma of thyroid with subcutaneous implantation was first reported. The patient with mucinous adenocarcinoma received six courses of TP regimen chemotherapy. Five cases received radioactive iodine therapy. After a mean of 69.5 months of follow-up, one case recurred in the lateral region, and no metastasis or recurrence happened in the other five cases. Although the implantation after thyroid surgery is uncommon, the cases serve as a reminder to take greater care to avoid implantation.

The classification of thyroid nodules, particularly those with a follicular growth pattern, has significantly evolved. These tumors, enriched with RAS or RAS-like mutations, remain challenging for pathologists due to variables such as nuclear atypia, invasion, mitotic activity, and tumor necrosis. This review addresses the histological correlates of benign, low-risk, and malignant RAS-mutant thyroid tumors, as well as some difficult-to-classify follicular nodules with worrisome features. One prototypical RAS-mutant nodule is non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). The assessment of nuclear characteristics in encapsulated/well-demarcated non-invasive RAS-mutant follicular-patterned tumors helps distinguish between follicular thyroid adenoma (FTA) and NIFTP. Despite this straightforward concept, questions about the degree of nuclear atypia necessary for the diagnosis of NIFTP are common in clinical practice. The nomenclature of follicular nodules lacking clear invasive features with increased mitotic activity, tumor necrosis, and/or high-risk mutations (e.g., TERT promoter or TP53) remains debated. Invasion, particularly angioinvasion, is the current hallmark of malignancy in RAS-mutant follicular-patterned neoplasms, with follicular thyroid carcinoma (FTC) as the model. Assessing the tumor interface is critical, though full capsule evaluation can be challenging. Multiple levels and NRASQ61R-specific immunohistochemistry can aid in identifying invasion. Controversies around vascular invasion persist, with ancillary stains like CD31, ERG, and CD61 aiding in its evaluation. Moreover, the review highlights that invasive encapsulated follicular variant papillary thyroid carcinoma (IEFVPTC) is closely associated with FTC, suggesting the need for better nomenclature. The concept of \"high-grade\" differentiated carcinomas, applicable to FTC or IEFVPTC with necrosis and/or high mitotic activity, is also discussed.

BACKGROUND: Anaplastic thyroid carcinoma(ATC) is a rare pathological type of thyroid malignancy. Primary squamous cell carcinoma of thyroid(PSCCT) is now considered as a subtype of ATC, hereinafter referred to as ATC-SCC subtype. ATC-SCC subtype combined with follicular thyroid carcinoma is exceedingly rare, with fewer cases reported. The ATC-SCC subtype is a highly invasive tumor with a poor prognosis for patients after metastasis occurs, and current treatment of this type of tumor is tricky.
METHODS: A 68-year-old female patient presented with a gradually growing swelling of right cervical region. Comprehensive auxiliary examinations and postoperative pathology confirmed the diagnosis of ATC-SCC subtype with follicular thyroid carcinoma, and the metastasis squamous cell carcinoma of the right cervical lymph nodes originates from ATC-SCC subtype. The patient received chemoradiotherapy postoperative. However, the residual cervical lymph nodes metastasis with squamous cell carcinoma still infiltrated surrounding structures in the neck extensively after palliative resection. The patient died 7 months after surgery.
CONCLUSIONS: Our case highlights that cervical lymph node metastasis may be a significant factor in the poor prognosis of ATC-SCC subtype. This malignancy should be detected and treated early.