Poorly differentiated thyroid carcinoma : An underdiagnosed entity

Management of Poorly Differentiated Thyroid Cancer and Differentiated High-Grade Thyroid Carcinoma

Thyroid carcinoma of follicular cell origin exists on a histopathologic and clinical spectrum. The authors focus on the category of tumors that fall between the very favorable well-differentiated thyroid carcinomas and the very unfavorable anaplastic thyroid carcinomas. These intermediately aggressive tumors include poorly differentiated thyroid carcinoma and the newly defined differentiated high-grade thyroid carcinoma. Both diagnoses require certain histopathologic requirements be met in order to accurately identify these tumors post-operatively. Management remains primarily surgical though adjunctive treatments such as molecular targeted therapies (eg, tyrosine kinase inhibitors) and differentiation therapy (to restore tumor response to radioactive iodine) are also becoming available.

Poorly Differentiated Thyroid Carcinoma in a 19-Year-Old Young Female Patient: A Case Report

Poorly differentiated thyroid carcinoma (PDTC) is a rare type of thyroid carcinoma that develops from follicular epithelial cells. In terms of morphology and prognosis, PDTC falls between well-differentiated thyroid carcinoma (WDTC) and anaplastic thyroid carcinoma (ATC). The spectrum of malignant thyroid tumors originating from follicles ranges from the fatal ATC at one end to the indolent WDTC at the other. We present a case of a 19-year-old female patient complaining of swelling on the right side of the neck. Computed tomography revealed a solid cystic lesion within the right lobe of the thyroid gland. The diagnosis of PDTC was made through histopathological examination. In this case, we evaluated the histological characteristics of the right lobe of the thyroid gland and presented a case report of PDTC in a young female.

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.

Poorly differentiated thyroid carcinoma arising from substernal goiter: a case report

Introduction and importance

Poorly differentiated thyroid carcinomas represent a rare heterogeneous group of malignant tumors that constitute ~2-4% of all thyroid neoplasms. Substernal goiter (SG) is defined as an enlargement of the thyroid gland that is located below the thoracic inlet. Malignant neoplasms arising from a SG were reported in only 2-3% of cases.This case report has been reported in line with the Surgical CAse REport (SCARE) Criteria.21.

Case presentation

This article presents a 54-year-old Syrian female who presented at our institution due to dysphagia, dyspnea, cervical swelling, and loss of appetite. Following clinical and radiological examinations, total thyroidectomy with lymph node dissection was performed. Microscopic examination revealed an infiltrative growth pattern of insular, trabecular, and solid formations of epithelial cells with scant eosinophilic cytoplasm, hyperchromatic nuclei, and bizarre mitotic figures with areas of necrosis. Subsequently, the final diagnosis was confirmed as a multifocal poorly differentiated thyroid carcinoma arising from a SG.

Clinical discussion

The heterogeneity of histologic features of poorly differentiated thyroid carcinoma represents a diagnostic challenge. Diagnosis of poorly differentiated thyroid carcinomas is based on the Turin Criteria, which highlights histopathological features. Computed tomography plays a major role in SG for further evaluation.

Conclusion

In this manuscript, the authors aimed to present a unique case report with challenging diagnostic features including the rapid development of an infiltrative poorly differentiated thyroid carcinoma from a SG highlighting the importance of a detailed histopathological examination of thyroid nodules in the absence of significant medical history.

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.

Cribriform Morular Thyroid Carcinoma - Ultimobranchial Pouch-Related? Deep Molecular Insights of a Unique Case

A 44-year-old female patient with a familial adenomatous polyposis (FAP) was diagnosed with a cribriform morular thyroid carcinoma (CMTC). We observed within the very necrotic tumor a small but distinct poorly differentiated carcinomatous component. As expected, next generation sequencing of both components revealed a homozygous APC mutation and in addition, a TERT promoter mutation. A TP53 mutation was found exclusively in the CMTC part, while the poorly differentiated component showed a clonal evolution, harboring an activating PIK3CA mutation and copy number gains of BRCA2, FGF23, FGFR1, and PIK3CB-alterations which are typically seen in squamous cell carcinoma. The mutational burden in both components was low, and there was no evidence for microsatellite instability. No mutations involving the mitogen-activated protein kinase (MAPK) pathway, typically seen in papillary thyroid carcinomas, were detected. Immunohistochemically, all tumor parts were negative for thyroglobulin, providing further evidence that this entity does not belong to the follicular epithelial cell-derived thyroid carcinoma group. CD5 was negative in the poorly differentiated component, making a relation to intrathyroidal thymic carcinoma rather unlikely. However, since this marker was seen in the morules, a loss in the poorly differentiated component and a relation to the ultimobranchial body cannot be excluded either. After total thyroidectomy and radioiodine ablation, the patient was disease-free with no residual tumor burden on 2-year follow-up.

DICER1 Mutations Do Not Always Indicate Dismal Prognosis in Pediatric Poorly Differentiated Thyroid Carcinomas

Progress in the field of pediatric thyroid pathology has linked DICER1 mutations to benign follicular cell-derived thyroid tumors (e.g., follicular adenoma with papillary architecture, follicular nodular disease), low-risk follicular cell-derived differentiated thyroid carcinomas and PDTCs enriched in fatal or recurrent/progressive disease. The dismal outcome of DICER1-harboring pediatric PDTCs stems from a limited number of reported patients' data given the rarity of pediatric PDTCs. In light of the former observations, the current study assessed clinicopathological variables of a series of 5 pediatric (≤ 18 years old) PDTCs using the Turin criteria (WHO 2022) and also examined the status of DICER1 and TERT promoter mutations. Five PDTCs (3 males, 2 females) were included in the study. The mean age at the time of diagnosis was 15.4 years. No patients had a history of DICER1 syndrome-related tumors or other clinicopathological diagnostic features of DICER1 syndrome. The mean tumor size was 3.9 cm. All tumors were completely submitted for microscopic examination. There was increased mitotic activity ranging from 3 to 10 mitoses per 2 mm2. Tumor necrosis was present in two cases. No PDTC harbored TERT promoter mutation. DICER1 hot spot mutation was identified in one (20%) tumor. The DICER1-mutant tumor had neither associated differentiated thyroid carcinoma component nor other pathological findings in the adjacent thyroid parenchyma. The DICER1-mutant PDTC showed widely invasive growth confined to the thyroid parenchyma. Despite the widely invasive growth, the tumor lacked vascular invasion. Two DICER1 wild-type PDTCs had lymphocytic thyroiditis and another one had underlying follicular nodular disease and/or follicular adenomas. Three DICER1 wild-type PDTCs also had an associated differentiated thyroid carcinoma component with no high-grade features. No abnormal p53 expression (overexpression or global loss) was recorded in all tested tumors. Four patients had follow-up data with a mean follow-up time of 60.25 months (range: 18-86 months). One patient with no evidence of disease recurrence died of an unrelated cause after 18 months of the initial surgery, all remaining patients were alive with no distant metastasis at their last visit. Of the 4 patients with lymph node (LN) dissection, one DICER1 wild-type PDTC had recurrent nodal disease. During the follow-up period (72 months), no local recurrence or distant metastases was detected in the DICER1-mutant PDTC. Taken together all reported findings from earlier series, DICER1 mutations alone may not necessarily indicate dismal outcome in a subset of pediatric PDTCs. The occurrence of additional genomic alterations as discussed in some earlier reports may be contributing to tumor progression or aggressivity of pediatric PDTCs. The lack of vascular invasion in the current DICER1-mutant pediatric PDTC may also explain an indolent biologic outcome. The risk escalation of DICER1 mutations should integrate the status of additional genetic events and well-established pathologic variables in order to ensure predictive dynamic risk stratification in DICER1-mutant pediatric PDTCs. Additional studies are needed to corroborate the findings of this study and advance our knowledge in pediatric thyroid neoplasia.

Revisiting the cytomorphological features of poorly differentiated thyroid carcinoma: a comparative analysis with indeterminate thyroid fine-needle aspiration samples

INTRODUCTION

Poorly differentiated thyroid carcinoma (PDTC) is an uncommon high-grade carcinoma of follicular cell origin that is usually overlooked on preoperative fine-needle aspiration (FNA) due to its rarity and cytomorphological overlap with follicular-patterned neoplasms. Definitive diagnosis of PDTC usually requires histologic examination of the resected thyroid tumor. Herein, we describe the cytological and architectural findings of histologically confirmed PDTC cases.

MATERIALS AND METHODS

A search for all thyroid FNAs with a corresponding surgical diagnosis of PDTC was performed. Surgical diagnoses were reviewed and confirmed using the Turin criteria. In addition, the control group consisted of indeterminate thyroid nodules (FLUS [follicular lesion of undetermined significance] and FN [follicular neoplasm]) that were either benign or well-differentiated thyroid tumors on resection. The PDTC and control groups were both subjected to cytological assessment using specific cytological and architectural parameters, which included cellularity, growth pattern, mitoses, necrosis, chromatin change, discohesion, and anisonucleosis.

RESULTS

A total of 36 thyroid FNAs were included in the study. This consisted of 12 histologically confirmed PDTC FNAs and 24 indeterminate thyroid FNAs (FLUS and FN, 12 each). The most frequent findings among PDTC groups were hypercellularity (75%), trabecular/insular growth pattern (58%), branching capillaries (67%), and cellular discohesion (92%). Necrosis (25%), ≥3 mitoses (50%), and anisonucleaosis (42%) were less frequently observed. A peculiar finding was the presence of adenoid cystic carcinoma-like globules in 50% of PDTC cases. Certain findings such as colloid, necrosis, mitoses, and cellular discohesion were helpful in differentiating the two groups.

CONCLUSIONS

Thyroid fine-needle aspiration remains an essential diagnostic/triage tool for most thyroid nodules/tumors. PDTC can be diagnosed or at least suspected preoperatively based on the demonstration of certain architectural and cytological alterations. Although mitoses and necroses are not always readily identified, an elevated Ki-67 labeling expression could provide additional clues to the diagnosis in some cases.

An Extremely Rare Case of Poorly Differentiated Thyroid Carcinoma Arising in Malignant Struma Ovarii and Concurrent Papillary Thyroid Carcinoma: A Case Study

Ovarian tumors can be classified by their origin - epithelial tumors, germ cell tumors, and stromal tumors. Malignant struma ovarii (MSO) are 0.01% of all ovarian tumors. In order to be classified as a struma ovarii, more than 50% of the teratoma consists of thyroid tissue. The thyroid tissue in the struma ovarii exhibits the same histological and physiological properties as that of the cervical thyroid tissue. Poorly differentiated thyroid carcinoma (PDTC) is an extremely rare occurrence when arising from an MSO. Including this case report, there are only 10 reports of PDTC in the setting of MSO. Of these cases, this patient is the only one who presented with concurrent primary thyroid carcinoma (PTC). This case study examines how invaluable intra-professional collaboration is for appropriate diagnosis, along with attention to detail of identifying markers in pathology sections and use of the appropriate immunohistochemical analysis.

Newly proposed survival staging system for poorly differentiated thyroid cancer: a SEER-based study

OBJECTIVE

Despite the recent release of the 8th edition TNM staging system, the risk stratification for poorly differentiated thyroid cancer (PDTC) remains controversial.

STUDY DESIGN

Retrospective study.

SETTING

SEER database and the First Hospital of China Medical University (FHCMU) database.

METHODS

Between 2004 and 2015, 1201 PDTC patients from the SEER database were enrolled to propose a new staging system. 38 PDTC patients were included from the FHCMU.

RESULTS

A retrospective analysis of 1201 PDTC cases was performed, and a new staging classification was developed as follows: stage I: age < 55 and T1/any N/M0 (n = 127, 10.57%); stage II: age < 55 and T2-4/any N/M0 or age ≥ 55 and T1-2/any N/M0 (n = 523, 43.55%); stage III: age < 55 and any T/N0/M1 or age ≥ 55 and any T3/any N/M0 (n = 239, 19.90%); stage IV: age < 55 and any T/N1/M1 or age ≥ 55 and T4/any N/M0, and T/any N/M1 (n = 312, 25.98%). The 10-year disease-specific survival rates of patients in the new stages I, II, III, and IV were 97.9%, 77.9%, 35.3%, and 12.1%, respectively. The proportion of variation explained (PVE) for disease-specific survival of the proposed system was higher than that of the 8th AJCC TNM staging (30.61% vs. 27.15%). The accuracy of the staging system was verified in 38 PDTC patients from the FHCMU.

CONCLUSION

The proposed staging system provided a more accurate risk stratification for PDTC patients. The new staging model may facilitate the design of personalized treatment strategies for PDTC patients.

No Longer Well-Differentiated: Diagnostic Criteria and Clinical Importance of Poorly Differentiated/High-Grade Thyroid Carcinoma

Poorly differentiated thyroid carcinoma (PDTC) and differentiated high-grade thyroid carcinoma (DHGTC) are uncommon thyroid malignancies, recently (re)codified into distinct entities with overlapping clinical significance. Recognizing them may be challenging for the general practitioner and subspecialty pathologist alike. This article will describe the required features to diagnose PDTC and DHGTC, differential diagnostic considerations, molecular findings, and clinical implications. It is intended to be a general synopsis of the most critical elements of PDTC and DHGTC as well as a summary of points in approaching these challenging cases.

High-Grade Non-Anaplastic Thyroid Carcinomas of Follicular Cell Origin: A Review of Poorly Differentiated and High-Grade Differentiated Carcinomas

Poorly differentiated thyroid carcinoma (PDTC) and high-grade differentiated thyroid carcinoma (HGDTC) are considered high-grade follicular-derived thyroid carcinomas, with prognoses intermediate between well-differentiated and anaplastic thyroid carcinoma. Both share the presence of invasion, thyroid follicular-cell origin, and tumor necrosis or increased mitoses (≥ 3 mitoses per 2 mm² in PDTC and ≥ 5 mitoses per 2 mm² in HGDTC), without anaplastic dedifferentiation. PDTC must possess solid, trabecular, or insular growth and lack classic papillary-like nuclei; HGDTC can be of any architectural or nuclear morphology (follicular-like, papillary-like, oncocytic). Transformation may be accompanied by acquisition of high-risk mutations (such as TP53 or TERT promoter) on top of RAS-like or BRAF p.V600E-like (including NTRK-fusion) initial driver mutations. These carcinomas most frequently affect adults and often present with metastases (20-50%) or wide local invasion. As PDTC and HGDTC may be radioactive iodine resistant, post-surgical therapy may consist of external beam radiotherapy or targeted, mutation-dependent chemotherapy, such as tyrosine kinase inhibitors. Ten-year disease specific survival is as low as 50%. Awareness of high-grade features in the diagnostic setting is important for patient prognosis and triage of tissue for molecular analysis in order to guide relevant clinical management and therapy.

Neutrophil-To-Lymphocyte Ratio is Associated With the Proportion of Poorly Differentiated Components in Papillary Thyroid Carcinoma

INTRODUCTION

Diagnosis of poorly differentiated thyroid cancer (PDTC) requires ≥ 50% of poorly differentiated components (PDC) in Japan. However, the optimal cutoff percentage of PDC for PDTC diagnosis remains controversial. Although high neutrophil-to-lymphocyte ratio (NLR) correlates with the aggressiveness of papillary thyroid cancer (PTC), whether NLR is associated with the proportion of PDC in PTC remains unstudied.

MATERIALS AND METHODS

Patients with the pure PTC (n = 664), PTC with < 50% PDC (n = 19), or PTC with ≥ 50% PDC (n = 26) who underwent surgery were retrospectively analyzed. Twelve-year disease-specific survival and preoperative NLR were compared among these groups.

RESULTS

Twenty seven patients died from thyroid cancer. The PTC with ≥ 50% PDC group (80.7%) showed significantly worse 12-year disease-specific survival than the pure PTC group (97.2%) (P < 0.001); however, the < 50% PDC group (94.7%) did not (P = 0.91). The PTC with ≥ 50% PDC group had a significantly higher NLR than the pure PTC (P < 0.001) and the PTC with < 50% PDC groups (P < 0.001), whereas there was no significant difference in the NLR between the pure PTC and the PTC with < 50% PDC groups (P = 0.48).

CONCLUSIONS

PTC with ≥ 50% PDC is more aggressive than either pure PTC or PTC with < 50% PDC, and NLR potentially reflects the PDC proportion. These results support the validity of 50% PDC as a cut-off for PDTC diagnosis and indicate the utility of NLR as a biomarker for PDC proportion.

Prospects of Testing Diurnal Profiles of Expressions of TSH-R and Circadian Clock Genes in Thyrocytes for Identification of Preoperative Biomarkers for Thyroid Carcinoma

Thyroid Nodules (TN) are frequent but mostly benign, and postoperative rate of benign TN attains the values from 70% to 90%. Therefore, there is an urgent need for identification of reliable preoperative diagnosis markers for patients with indeterminate thyroid cytology. In this study, an earlier unexplored design of research on preoperative biomarkers for thyroid malignancies was proposed. Evaluation of reported results of studies addressing the links of thyroid cancer to the circadian clockwork dysfunctions and abnormal activities of Thyroid-Stimulating Hormone (TSH) and its receptor (TSH-R) suggested diagnostic significance of such links. However, there is still a gap in studies of interrelationships between diurnal profiles of expression of circadian clock genes and TSH-R in indeterminate thyroid tissue exposed to different concentrations of TSH. These interrelationships might be investigated in future in vitro experiments on benign and malignant thyrocytes cultivated under normal and challenged TSH levels. Their design requires simultaneous measurement of diurnal profiles of expression of both circadian clock genes and TSH-R. Experimental results might help to bridge previous studies of preoperative biomarkers for thyroid carcinoma exploring diagnostic value of diurnal profiles of serum TSH levels, expression of TSH-R, and expression of circadian clock genes.

Poorly differentiated thyroid carcinoma arising from a lithium-induced goiter in a patient with schizophrenia: a case report

BACKGROUND

Lithium use causes goiter by increasing serum thyroid-stimulating hormone levels through the inhibition of thyroid hormone release. However, there are no reports of poorly differentiated thyroid carcinoma resulting from lithium-induced goiter. Herein, we report the case of a patient with schizophrenia who developed poorly differentiated thyroid carcinoma arising from a lithium-induced goiter.

CASE PRESENTATION

A 61-year-old woman who was taking lithium for schizophrenia, visited the thyroid-endocrine center with a 10 × 12 cm anterior neck mass. She had a slowly growing goiter approximately 30 years ago; however, when she came to the hospital for diabetes diagnosis 2 years ago, she had no accompanying symptoms and refused evaluation. Three months before her visit, her dysphagia and dyspnea worsened as the size of her goiter increased rapidly. A neck ultrasound and enhanced thyroid computed tomography (CT) examination revealed a 10.9 × 9.2 × 12.8 cm size multi-lobulated mass on the right thyroid gland, leading to a leftward deviation of the trachea. Diagnostic total thyroidectomy was performed, and microscopic findings and immunohistochemical staining results indicated poorly differentiated thyroid carcinoma (PDTC) in the right thyroid mass. Mutation analyses for BRAF and the telomerase reverse transcriptase (TERT) promoter was performed. No BRAF gene mutations were detected; however, TERT promoter C228T point mutation was present in the PDTC. The patient underwent radioactive iodine therapy two months after the surgery. At a recent follow-up 4 months postoperatively, she was taking thyroid hormone replacement and remained in a relatively good health with a serum thyroglobulin level of 0.55 ng/ml.

CONCLUSIONS

Thyroid examination of psychiatric patients who develop goiter due to long-term lithium treatment should be monitored regularly, and appropriate investigations and surgery should be performed in a timely manner if the goiter is growing rapidly.

[Molecular genotyping in refractory thyroid cancers in 2021: When, how and why? A review from the TUTHYREF network]

Refractory thyroid cancers include radio-iodine-refractory cancers, metastatic or locally advanced unresectable medullary and anaplastic thyroid cancers. Their management has been based for several years on the use of multi-target kinase inhibitors, with anti-angiogenic action, with the exception of anaplastic cancers usually treated with chemo- and radiotherapy. The situation has recently evolved due to the availability of molecular genotyping techniques allowing the discovery of rare but targetable molecular abnormalities. New treatment options have become available, more effective and less toxic than the previously available multi-target kinase inhibitors. The management of refractory thyroid cancers is therefore becoming more complex both at a diagnosis level with the need to know when, how and why to look for these molecular abnormalities but also at a therapeutic level, innovative treatments being hardly accessible. The cost of molecular analyzes and the access to treatments need also to be homogenized because disparities could lead to inequality of care at a national or international level. Finally, the strategy of identifying molecular alterations and treating these rare tumors reinforces the importance of a discussion in a multidisciplinary consultation meeting.

Development of Novel Follicular Thyroid Cancer Models Which Progress to Poorly Differentiated and Anaplastic Thyroid Cancer

Recent developments in thyroid cancer research have been hindered by a lack of validated in vitro models, allowing for preclinical experimentation and the screening of prospective therapeutics. The goal of this work is to develop and characterize three novel follicular thyroid cancer (FTC) cell lines developed from relevant animal models. These cell lines recapitulate the genetics and histopathological features of FTC, as well as progression to a poorly differentiated state. We demonstrate that these cell lines can be used for a variety of in vitro applications and maintain the potential for in vivo transplantation into immunocompetent hosts. Further, cell lines exhibit differing degrees of dysregulated growth and invasive behavior that may help define mechanisms of pathogenesis underlying the heterogeneity present in the patient population. We believe these novel cell lines will provide powerful tools for investigating the molecular basis of thyroid cancer progression and lead to the development of more personalized diagnostic and treatment strategies.

Thyroid Carcinoma: Phenotypic Features, Underlying Biology and Potential Relevance for Targeting Therapy

Thyroid carcinoma consists a group of phenotypically heterogeneous cancers. Recent advances in biological technologies have been advancing the delineation of genetic, epigenetic, and non-genetic factors that contribute to the heterogeneities of these cancers. In this review article, we discuss new findings that are greatly improving the understanding of thyroid cancer biology and facilitating the identification of novel targets for therapeutic intervention. We review the phenotypic features of different subtypes of thyroid cancers and their underlying biology. We discuss recent discoveries in thyroid cancer heterogeneities and the critical mechanisms contributing to the heterogeneity with emphases on genetic and epigenetic factors, cancer stemness traits, and tumor microenvironments. We also discuss the potential relevance of the intratumor heterogeneity in understanding therapeutic resistance and how new findings in tumor biology can facilitate designing novel targeting therapies for thyroid cancer.

Which is preferred for initial treatment of papillary thyroid cancer, total thyroidectomy or lobotomy?

Purposes

The incidence of thyroid cancer has increased annually, and has a heavy psychological and economic burden on society and individuals. Based thyroid cancer data from patients treated in Liaocheng People's Hospital from 2015 to 2018, with Chinese national and regional characteristics, in this study, we addressed the controversy of which initial thyroid surgical mode, lobectomy or total thyroidectomy, is most effective.

Methods

Clinical and pathological data from 2108 patients with thyroid cancer, who were initially diagnosed and treated surgically, were collected from the Department of Thyroid Surgery. Among them, there were 1001 cases who underwent open operation with total thyroidectomy + central lymph node dissection; meanwhile, 1107 cases were treated with neck lateral lymph node dissection at the same time.

Results

The overall metastasis rate of all patients was 57.23%. Even the lymph node metastasis of papillary thyroid microcarcinoma (PTMC) was as high as 48.97%. When the mass rose above 2 cm, the proportion of metastasis increased to 77.22%. When the tumor was complicated with bilateral and multiple high‐risk factors, the proportion of metastasis was 65.27% and 72.21%, respectively. When the tumor breaks through the capsule, the metastasis rate was 67.08%. With the increase of tumor diameter, the metastasis of cervical lymph nodes ranged from 22.54% to 73.33%, which showed positive correlation. 49.32% of patients had lymph node metastasis in the lateral cervical region. When the diameter of the tumor reached T1c level, the metastasis of the cervical lymph nodes was 56.91%, and the number of metastatic cases above T1c level accounted for 69.96% of the total metastatic cases.

Conclusion

The degree of malignancy of thyroid cancer depends on tumor genome evolution. Rates of neck lymph node metastasis are high, particularly among patients with risk factors for poor prognosis. It is recommended that initial treatment should comprise at least total thyroidectomy + central lymph node dissection in China, to avoid the risks associated with secondary surgery and effects on patient quality of life. When the tumor diameter exceeds 1 cm, the risk of cervical lymph node metastasis is high, and we recommended lateral lymph node dissection.

Genetics, Diagnosis, and Management of Hürthle Cell Thyroid Neoplasms

Hürthle cell lesions have been a diagnostic conundrum in pathology since they were first recognized over a century ago. Controversy as to the name of the cell, the origin of the cell, and even which cells in particular may be designated as such still challenge pathologists and confound those treating patients with a diagnosis of "Hürthle cell" anything within the diagnosis, especially if that anything is a sizable mass lesion. The diagnosis of Hürthle cell adenoma (HCA) or Hürthle cell carcinoma (HCC) has typically relied on a judgement call by pathologists as to the presence or absence of capsular and/or vascular invasion of the adjacent thyroid parenchyma, easy to note in widely invasive disease and a somewhat subjective diagnosis for minimally invasive or borderline invasive disease. Diagnostic specificity, which has incorporated a sharp increase in molecular genetic studies of thyroid tumor subtypes and the integration of molecular testing into preoperative management protocols, continues to be challenged by Hürthle cell neoplasia. Here, we provide the improving yet still murky state of what is known about Hürthle cell tumor genetics, clinical management, and based upon what we are learning about the genetics of other thyroid tumors, how to manage expectations, by pathologists, clinicians, and patients, for more actionable, precise classifications of Hürthle cell tumors of the thyroid.

The Oncocytic Variant of Poorly Differentiated Thyroid Carcinoma Shows a Specific Immune-Related Gene Expression Profile

BACKGROUND

Poorly differentiated thyroid cancer (PDTC) is a rare, follicular cell-derived neoplasm with an unfavorable prognosis. The oncocytic variant of PDTC may be associated with even more adverse outcome than classical PDTC cases, but its specific molecular features are largely unknown. Our aim was to explore the immune-related gene expression profile of oncocytic and classical PDTC, in correlation with clinical and pathological characteristics (including programmed death ligand 1 [PD-L1] expression) and outcome, and in comparison with a control group of well-differentiated follicular carcinomas (WDFCs), including conventional follicular carcinomas (FTCs) and Hürthle cell carcinomas (HCCs).

METHODS

A retrospective series of 48 PDTCs and 24 WDFCs was analyzed by means of NanoString technology employing the nCounter PanCancer Immune Profiling panel. Gene expression data were validated using quantitative real-time polymerase chain reaction.

RESULTS

Oncocytic PDTCs showed a specific immune-related gene expression profile, with higher expression of LAIR2, CD274, DEFB1, IRAK1, CAMP, LCN2, LY96, and APOE, and lower expression of NOD1, as compared to conventional PDTCs. This molecular signature was associated with increased intratumoral lymphocytic infiltration, PD-L1 expression, and adverse outcome. Three of these genes, CD274, DEFB1, and IRAK1, as well as PD-L1 expression, were also the hallmarks of HCCs as compared to FTCs. By contrast, the panel of genes differentially regulated in PDTCs as compared to WDFCs was unrelated to the oncocytic phenotype.

CONCLUSIONS

Our results revealed a distinctive immune-related gene expression profile of oncocytic PDTC and confirmed a more aggressive outcome in this cancer subtype. These findings may provide guidance when exploring novel immunotherapeutic options for oncocytic PDTC patients.

With High-Risk Factors, Total Thyroidectomy is Preferred for Thyroid Cancer

INTRODUCTION

Based on thyroid cancer data from patients treated in Liaocheng People's Hospital in 2017, with Chinese national and regional characteristics, in this study we addressed the controversy of which initial thyroid surgical mode, lobectomy or total thyroidectomy, is most effective.

PATIENTS AND METHODS

Clinical and pathological data from 552 patients with thyroid cancer, who were initially diagnosed and treated surgically, were collected from the Department of Thyroid Surgery. Among them, 40 patients underwent endoscopic surgery, with resection including lobectomy + central lymph node dissection of the affected lobe, while 512 cases underwent total thyroidectomy + central lymph node dissection.

RESULTS

The metastasis rate for all patients was 59.42%. Further, among patients with bilateral or multiple tumors or capsule invasion, the proportions who developed metastatic disease were 63.54% and 71.19% and 67.46%, respectively. Meanwhile, the incidence of contralateral accidental malignancy was 7.25% after postoperative paraffin pathology.

DISCUSSION

Rates of neck lymph node metastasis are high, particularly among patients with risk factors for poor prognosis. It is recommended that, among patients with risk factors, initial treatment should comprise at least total thyroidectomy + central lymph node dissection in China, to avoid the risks associated with secondary surgery and effects on patient quality of life.

Solid variant of papillary thyroid carcinoma: an under-recognized entity

Solid variant of papillary thyroid carcinoma (SVPTC) is a rare morphological variant of papillary thyroid carcinoma (PTC). SVPTC is histologically characterized by predominant solid, trabecular and insular nests of tumor cells while cytological features of PTC such as nuclear grooves and nuclear inclusions are preserved. In fine needle aspiration cytology smears, tumor cells of SVPTC may be presented in cohesive, syncytial or trabecular clusters accompanied by some discohesiveness in the absence of necrosis. Although SVPTC and poorly differentiated thyroid carcinoma (PDTC) share similar histological findings of solid nests, SVPTC can be differentiated from PDTC in the lack of tumor necrosis, severe nuclear atypia, and a higher mitotic index. Immunohistochemical expression of CK19 and HBME-1, common markers of PTC, is decreased in solid nests of SVPTC. In pediatric patients exposed to radiation after the Chernobyl nuclear accident, there was a higher prevalence of SVPTC with RET/PTC3 type rearrangement. BRAF mutations are also reported in a small number of adult patients with SVPTC without any prior radiation exposure. Patients with SVPTC may have a slightly higher incidence of metastasis and recurrence of the tumor compared to conventional PTC, although overall survival rate is comparable. In this article, the current knowledge of SVPTC will be reviewed and discussed with an emphasis on the histopathological feature.

Thyroid Tumors You Don't Want to Miss

This article examines more uncommon thyroid entities, including anaplastic thyroid carcinoma, poorly differentiated thyroid carcinoma, rare papillary thyroid carcinoma variants, medullary thyroid carcinoma, non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), and multiple adenomatous nodules in the setting of Cowden syndrome. These entities were chosen based on their clinical significance and because they can be diagnostically challenging due to their morphologic diversity and overlap with other thyroid tumors. This article addresses the diagnostic features of each entity, focusing on how to avoid potential pitfalls and mimics while also highlighting the clinical implications of each diagnosis.