Mutations of TSHR and TP53 Genes in an Aggressive Clear Cell Follicular Carcinoma of the Thyroid

The role of the hypothalamic-pituitary-thyroid axis in thyroid cancer

The hypothalamic-pituitary-thyroid axis plays a crucial role in the pathogenesis, diagnosis, risk stratification, effectiveness of radioiodine therapy, and treatment response evaluation in epithelial thyroid cancer. Supraphysiological doses of levothyroxine are used in patients with intermediate-risk and high-risk thyroid cancer to suppress thyroid-stimulating hormone (TSH) to prevent tumour progression. However, free thyroxine and tri-iodothyronine have also been found to promote tumour growth in thyroid cancer preclinical models. Moreover, current evidence remains inconclusive about the role of TSH suppression in improving survival outcomes and reveals an increased risk of cardiovascular and skeletal adverse events after long-term exposure to excess levothyroxine. Stimulation of the axis with either recombinant human TSH or thyroid hormone withdrawal has been proven equally effective for diagnostic purposes and for facilitating radioiodine uptake for thyroid remnant ablation, but evidence is insufficient for non-inferiority of recombinant human TSH-based vs thyroid hormone withdrawal-based stimulation before radioiodine therapy of distant metastases.

Multi-Omics and Management of Follicular Carcinoma of the Thyroid

Follicular thyroid carcinoma (FTC) is the second most common cancer of the thyroid gland, accounting for up to 20% of all primary malignant tumors in iodine-replete areas. The diagnostic work-up, staging, risk stratification, management, and follow-up strategies in patients who have FTC are modeled after those of papillary thyroid carcinoma (PTC), even though FTC is more aggressive. FTC has a greater propensity for haematogenous metastasis than PTC. Furthermore, FTC is a phenotypically and genotypically heterogeneous disease. The diagnosis and identification of markers of an aggressive FTC depend on the expertise and thoroughness of pathologists during histopathological analysis. An untreated or metastatic FTC is likely to de-differentiate and become poorly differentiated or undifferentiated and resistant to standard treatment. While thyroid lobectomy is adequate for the treatment of selected patients who have low-risk FTC, it is not advisable for patients whose tumor is larger than 4 cm in diameter or has extensive extra-thyroidal extension. Lobectomy is also not adequate for tumors that have aggressive mutations. Although the prognosis for over 80% of PTC and FTC is good, nearly 20% of the tumors behave aggressively. The introduction of radiomics, pathomics, genomics, transcriptomics, metabolomics, and liquid biopsy have led to improvements in the understanding of tumorigenesis, progression, treatment response, and prognostication of thyroid cancer. The article reviews the challenges that are encountered during the diagnostic work-up, staging, risk stratification, management, and follow-up of patients who have FTC. How the application of multi-omics can strengthen decision-making during the management of follicular carcinoma is also discussed.

G Protein-Coupled receptors and heterotrimeric G proteins as cancer drivers

G protein-coupled receptors (GPCRs) and heterotrimeric G proteins play central roles in a diverse array of cellular processes. As such, dysregulation of GPCRs and their coupled heterotrimeric G proteins can dramatically alter the signalling landscape and functional state of a cell. Consistent with their fundamental physiological functions, GPCRs and their effector heterotrimeric G proteins are implicated in some of the most prevalent human diseases, including a complex disease such as cancer that causes significant morbidity and mortality worldwide. GPCR/G protein-mediated signalling impacts oncogenesis at multiple levels by regulating tumour angiogenesis, immune evasion, metastasis, and drug resistance. Here, we summarize the growing body of research on GPCRs and their effector heterotrimeric G proteins as drivers of cancer initiation and progression, and as emerging antitumoural therapeutic targets.

Pitfalls in Challenging Thyroid Tumors: Emphasis on Differential Diagnosis and Ancillary Biomarkers

Thyroid pathology encompasses a heterogenous group of clinicopathological entities including rare and diagnostically challenging neoplasms. The review is focused on morphological, immunohistochemical, and molecular features of rare thyroid neoplasms that can pose diagnostic problems. The tumors are organized based on growth patterns including thyroid neoplasms with predominantly papillary, follicular, solid, and spindle cell growth pattern, as well as neoplasms with distinct cytological characteristics. A special section is also dedicated to rare thyroid tumors with peculiar patterns including thyroid carcinoma with Ewing family tumor elements and intrathyroidal thymic-related neoplasms.

Clear Cell Variant of Papillary Thyroid Carcinoma With Associated Anaplastic Thyroid Carcinoma: Description of an Extraordinary Case

Clear cell change is a rare observation in thyroid cancer, resulting from aberrant cytoplasmic accumulation of lipids, glycogen, or thyroglobulin in the tumor cells. The phenomenon is most common for follicular thyroid neoplasia, with no definite coupling to patient outcome. The clear cell variant of papillary thyroid carcinoma (ccPTC) is even more infrequent-making conclusions regarding prognosis difficult. Single reports describe distant metastases of ccPTCs as well as co-occurrence with anaplastic thyroid carcinoma (ATC). In this report, a case of a therapy-resistant ccPTC dedifferentiating into an ATC is characterized from morphological and immunohistochemical standpoints. The patient was a 79-year-old female presenting with a 45-mm nodule in her right thyroid lobe. A first round of cytology raised the suspicion of PTC, but a repeated biopsy verified an ATC diagnosis. Neoadjuvant doxorubicin and external irradiation therapy was administered, and the patient developed lung metastases concomitantly. A palliative lobectomy was performed, and the final diagnosis was a ccPTC with focal dedifferentiation into an ATC. Intriguingly, the ccPTC component was viable and dominated the lesion. The clear cell morphology stemmed from an accumulation of glycogen, while the anaplastic component was devoid of evident clear cell changes. The case is one of exceedingly few descriptions of a ccPTC that dedifferentiates to an ATC, suggesting that this PTC subtype is not without potential for development of a highly lethal tumor component. Moreover, the partial lack of response to neoadjuvant therapy suggests a possible underlying resistance to aggressive treatment modalities in this particular case.

A review on the mechanism of iodide metabolic dysfunction in differentiated thyroid cancer

The incidence of differentiated thyroid cancer (DTC) has been increasing rapidly worldwide, and the risk factors remain unclear. With the growing number of patients with DTC, the related issues have been gradually highlighted. ¹³¹Iodide (¹³¹I) is an important treatment for DTC and has the potential to reduce the risk of recurrence. ¹³¹I is also an effective treatment for distant metastases of thyroid carcinoma. However, iodide metabolism dysfunction in metastatic foci causes patients to lose the opportunity of ¹³¹I treatment. This article reviews the related mechanisms of iodide metabolism dysfunction in DTC cells and summarizes the clinical transformation progression.

RET/PTC Gene Rearrangements in Thyroid Carcinogenesis: Assessment and Clinico-Pathological Correlations

Rearranged during transfection (RET) is a proto oncogene implicated in thyroid carcinogenesis of papillary type (PTC). The RET proto-oncogene in PTC is constitutively activated by fusion of its tyrosine kinase domain with the 5 ´region of another gene thereby generating chimeric products collectively named RET/PTCs. RET/PTC1 and RET/PTC3 are best characterized among all RET/PTC rearrangements. Kashmir valley has witnessed an alarming increase in thyroid cancer incidence in young women. Therefore, we investigated the occurrence of RET/PTC 1 & 3 rearrangements by semi quantitative and qPCR in thyroid cancer patients (n = 48) of Kashmiri population and interrelated results with various clinicopathological characteristics. We observed that all the RET/PTC rearrangements were confined to PTC cases (10/40). Presence of RET/PTC rearrangement significantly correlated with gender, elevated TSH levels and lymph node metastasis. Overall, our study advocates that RET/PTC3 rearrangement is a frequent event in the carcinogenesis of thyroid gland in Kashmiri population although a study with a larger sample size is needed to get a clear scenario.

Clear Cell Variant of a Follicular Thyroid Tumor With Uncertain Malignant Potential: A Case Report

Follicular neoplasms of the thyroid gland are most often characterized by follicular-patterned thyrocytes with a neutrally stained cytoplasm, while a minority of cases present with oncocytic differentiation (Hürthle cell tumors). Exceedingly rare variants with a clear cell phenotype have also been reported, both as clear cell follicular thyroid adenomas (ccFTAs) and clear cell follicular carcinomas (ccFTCs). We present a patient with a 30-mm lesion in the thyroid isthmus in which the preoperative cytology proposed a follicular tumor. On postoperative histopathological evaluation, the tumor surprisingly displayed uniform clear-cell differentiation. No nuclear features suggestive of papillary thyroid carcinoma were observed, and differential diagnoses such as medullary thyroid carcinoma, metastatic renal cell, and parathyroid carcinoma were ruled out. The histological investigation revealed intracapsular collections of tumor cells displaying a debatable relation to the surrounding capsule and blood vessels, and the final diagnosis was a follicular tumor of uncertain malignant potential (FT-UMP) as defined by the WHO 2017 classification. As subsets of FT-UMPs with TERT promoter mutations do recur as advanced malignant tumors, a sequencing analysis was undertaken but could not identify TERT promoter mutations at position C228 or C250. To our knowledge, no previous literature has described a clear cell phenotype in an FT-UMP. We therefore advocate that endocrine pathologists should be aware of this entity in addition to ccFTAs and ccFTCs.

BRAFwild papillary thyroid carcinoma has two distinct mRNA expression patterns with different clinical behaviors

BACKGROUND

Using a large set of genomic data from The Cancer Genome Atlas (TCGA), we classified BRAF^wild papillary thyroid carcinomas (PTCs) into 2 subtypes with distinct molecular patterns and different clinical behaviors. We also suggested gene signatures (RAS-score) to predict molecular subtypes and clinical behaviors of BRAF^wild PTC.

METHOD

Integrated genomic analysis was done using all genomic data of PTC in TCGA data portal (https://tcga-data.nci.nih.gov) and cancer browser (https://genome-cancer.ucsc.edu). Using Gene Ontology and a logistic regression test, we selected gene signatures (RAS-score) and applied this prediction model to the validation cohort (GSE60542).

RESULT

When we performed multiplatform genomic analysis, BRAF^wild PTCs were divided into 2 molecular subtypes. Each subtype showed distinct molecular patterns and clinical behaviors. Gene signatures successfully predicted molecular subtype in another validation cohort.

CONCLUSION

We found that BRAF^wild PTCs were divided into 2 molecular subtypes and each subtype showed distinct molecular patterns, different activated pathways, and different clinical behaviors.

Clear Cell Change in Thyroid Carcinoma: A Clinicopathologic and Molecular Study with Identification of Variable Genetic Anomalies

BACKGROUND

Clear-cell carcinoma of the thyroid has been regarded as a variant of follicular (FTC) or papillary (PTC) thyroid carcinoma. Twenty-one primary thyroid carcinomas with clear-cell features, diagnosed in 20 patients (12 female) were identified between 1992 and 2012 (0.5% of in-house thyroid carcinomas).

METHODS

Hematoxylin and eosin slides were reviewed. SNaPshot multigene mutational analysis and a translocation panel were successfully performed on 15 of these cases.

RESULTS

Twelve (57%) were FTC, five were conventional PTC, two were follicular variant of PTC, and two were poorly differentiated thyroid carcinomas. Five cases had RAS mutation (four FTC and one PTC); two had PAX8-PPARgamma translocations (both FTC, one with concurrent p53 mutation); one had an EML4-ALK translocation (PTC); and one had a TFG-MET translocation (follicular variant of PTC). Five carcinomas were metastatic to regional lymph nodes (three FTC and two PTC), and two were metastatic to bone (both FTC). Disease confined to the thyroid (67%) and rates of regional lymph node metastasis (24%) and distant metastasis (10%) were near the national averages (68%, 25%, and 5%, respectively). One patient with a poorly differentiated thyroid carcinoma died one year after diagnosis, and a patient with metastatic FTC died two years after diagnosis. Overall mortality was 10%.

CONCLUSIONS

Clear-cell change in thyroid carcinoma is rare, is more common in FTC than it is in PTC, is found focally or multifocally within a given lesion, and is frequently associated with RAS mutations (33%). Clear-cell change in thyroid neoplasia should raise the possibility of follicular carcinoma, and should not be treated differently from other carcinomas of similar grade and stage.

The Art and Science of Thyroid Surgery in the Age of Genomics: 100 years after Theodor Kocher

Cancer is a disorder of the genome. The thyroid cancer genome is being decoded. Recent studies have identified a mutation or a genetic alteration in 95% of thyroid cancers. The National Cancer Institute initiated the Cancer Genome Atlas project in 2006 to catalogue genetic mutations associated with cancer, using genome sequencing and bioinformatics. The project has expanded to carry out genomic characterization and sequence analysis of thyroid cancer. The concept of risk stratification based on traditional parameters will soon vacate their role for clear molecular markers of non-invasive/focal, invasive/metastatic and systemic stages/phases of neoplastic disorder. A refined classification scheme based on genomics and its phenotypic expressions will accurately reflect the biologic differences between the different morphologic definitions we use today. Tumor differentiation/de-differentiation, and clinical behavior of an individual cancer will be defined by molecular markers, in addition to standard morpho-pathology. Empiricism in science of medicine and surgery has acquired a new method for testing the appropriate treatment for individual patients; that is molecular pathology, governed by genomics. The technology is present and rapidly evolving. The surgeons will determine the extent of interventions with molecular evidence and guidance.

Targeted Next-Generation Sequencing Analysis of a Pendred Syndrome-Associated Thyroid Carcinoma

Pendred syndrome is an autosomal recessive disorder characterized by hearing loss and goiter and is caused by bi-allelic mutations (homozygous or compound heterozygous) of the PDS (SLC26A4) gene. The incidence of Pendred syndrome is 7.5-10/100,000 in the general population, and it carries a 1 % risk of developing thyroid carcinoma. Herein, we report a case of a patient with Pendred syndrome who developed a follicular variant of papillary thyroid carcinoma (FVPTC)-that is approximately at an odd of 1/1,000,000. Targeted next-generation sequencing with ThyroSeq v2 was performed on the tumor, and only a TP53 mutation (TP53 p.R175H) was identified. The mutation was limited to the tumor nodule of FVPTC as shown by immunohistochemistry. This report represents the first extensive molecular study of a Pendred syndrome-associated thyroid carcinoma. The evidences support that thyroid carcinomas arising from dyshormonogenetic goiter require additional genetic alteration in addition to the purported thyroid-stimulating hormone (TSH) overstimulation. It is intrigue to note that the mutant p53 is involved in the development of a low-grade malignant thyroid tumor as FVPTC in this patient.