Anaplastic thyroid carcinoma with rhabdoid features

Anaplastic thyroid cancer spheroids as preclinical models to test therapeutics

Anaplastic thyroid cancer (ATC) is the most aggressive thyroid cancer. Despite advances in tissue culture techniques, a robust model for ATC spheroid culture is yet to be developed. In this study, we created an efficient and cost-effective 3D tumor spheroids culture system from human ATC cells and existing cell lines that better mimic patient tumors and that can enhance our understanding of in vivo treatment response. We found that patient-derived ATC cells and cell lines can readily form spheroids in culture with a unique morphology, size, and cytoskeletal organization. We observed both cohesive (dense and solid structures) and discohesive (irregularly shaped structures) spheroids within the same culture condition across different cell lines. BRAFWT ATC spheroids grew in a cohesive pattern, while BRAFV600E-mutant ATC spheroids had a discohesive organization. In the patient-derived BRAFV600E-mutant ATC spheroids, we observed both growth patterns, but mostly the discohesive type. Histologically, ATC spheroids had a similar morphology to the patient's tumor through H&E staining and proliferation marker staining. Moreover, RNA sequencing analysis revealed that the gene expression profile of tumor cells derived from the spheroids closely matched parental patient tumor-derived cells in comparison to monolayer cultures. In addition, treatment response to combined BRAF and MEK inhibition in BRAFV600E-mutant ATC spheroids exhibited a similar sensitivity to the patient clinical response. Our study provides a robust and novel ex vivo spheroid model system that can be used in both established ATC cell lines and patient-derived tumor samples to better understand the biology of ATC and to test therapeutics.

Evaluation of E-Cadherin and β-Catenin Immunoreactivity for Determining Undifferentiated Cells in Anaplastic Thyroid Carcinoma

INTRODUCTION

An immunohistochemical study has occasionally been performed to diagnose anaplastic thyroid carcinoma (ATC). However, antibodies to confirm the undifferentiated nature of ATC have not yet been evaluated. The aim of this study was to evaluate E-cadherin and β-catenin expressions in immunoreactivity to determine undifferentiated carcinoma cells in the diagnosis of ATC.

METHODS

We immunohistochemically examined 29 ATCs, 30 poorly differentiated thyroid carcinomas (PDTCs), 22 well-differentiated thyroid carcinomas (WDTCs), and 3 squamous cell carcinomas. Antibodies for thyroid transcription factor-1 (TTF-1), paired-box gene 8 (PAX8), β-catenin, and E-cadherin were used.

RESULTS

All WDTCs tested positive for TTF-1, PAX8, and E-cadherin. The positive rates of TTF-1, PAX8, and E-cadherin were 93.3, 93.3, and 100%, respectively, in PDTCs and 17.2, 51.7, and 10.3%, respectively, in ATCs. WDTC expressed the lateral cell membrane staining for β-catenin and E-cadherin, whereas PDTC showed circumferential cell membranous expression (fishnet pattern). β-catenin cell membrane expression in ATCs is lost or discontinuous. Carcinoma cells with β-catenin nuclear expression without cell membranous expression were scattered in 72.4% of ATCs but were not observed in the other carcinomas.

CONCLUSION

We propose 3 immunohistochemical findings to determine undifferentiated carcinoma cells in the diagnosis of ATC: (1) β-catenin nuclear expression with no or reduced cell membranous expression, (2) the loss or discontinuous pattern of E-cadherin expression, and (3) the loss of PAX8 nuclear expression.

2021 American Thyroid Association Guidelines for Management of Patients with Anaplastic Thyroid Cancer

Background: Anaplastic thyroid cancer (ATC) is a rare but highly lethal form of thyroid cancer. Since the guidelines for the management of ATC by the American Thyroid Association were first published in 2012, significant clinical and scientific advances have occurred in the field. The aim of these guidelines is to inform clinicians, patients, and researchers on published evidence relating to the diagnosis and management of ATC. Methods: The specific clinical questions and topics addressed in these guidelines were based on prior versions of the guidelines, stakeholder input, and input of the Task Force members (authors of the guideline). Relevant literature was reviewed, including serial PubMed searches supplemented with additional articles. The American College of Physicians Guideline Grading System was used for critical appraisal of evidence and grading strength of recommendations. Results: The guidelines include the diagnosis, initial evaluation, establishment of treatment goals, approaches to locoregional disease (surgery, radiotherapy, targeted/systemic therapy, supportive care during active therapy), approaches to advanced/metastatic disease, palliative care options, surveillance and long-term monitoring, and ethical issues, including end of life. The guidelines include 31 recommendations and 16 good practice statements. Conclusions: We have developed evidence-based recommendations to inform clinical decision-making in the management of ATC. While all care must be individualized, such recommendations provide, in our opinion, optimal care paradigms for patients with ATC.

Comprehensive guidance on the diagnosis and management of primary mesenchymal tumours of the thyroid gland

Most primary thyroid tumours are of epithelial origin. Primary thyroid mesenchymal tumours are rare but are being increasingly detected. A vast majority of thyroid mesenchymal tumours occur between the fourth and seventh decades of life, presenting as progressively enlarging thyroid nodules that often yield non-diagnostic results or spindle cells on fine needle aspiration biopsy. Surgery is the preferred mode of treatment, with adjuvant chemoradiotherapy used for malignant thyroid mesenchymal tumours. Benign thyroid mesenchymal tumours have excellent prognosis, whereas the outcome of malignant thyroid mesenchymal tumours is variable. Each thyroid mesenchymal tumour is characterised by its unique histopathology and immunohistochemistry. Because of the rarity and aggressive nature of malignant thyroid mesenchymal tumours, a multidisciplinary team-based approach should ideally be used in the management of these tumours. Comprehensive guidelines on the management of thyroid mesenchymal tumours are currently lacking. In this Review, we provide a detailed description of thyroid mesenchymal tumours, their clinical characteristics and tumour behaviour, and provide recommendations for the optimal management of these tumours.

Anaplastic thyroid carcinoma: Updates on WHO classification, clinicopathological features and staging

Anaplastic thyroid carcinoma is an uncommon carcinoma representing 1 to 4% of all thyroid cancers. The carcinoma is most common in females of the eight decades. It is a locally advanced cancer with frequent infiltration of surrounding organs, blood vessels and skin of neck. Paraneoplastic manifestations could occur. Approximately half of the patients with anaplastic thyroid carcinoma had distant metastasis with lung and brain as the most frequent sites of metastasis. The median survival of patients with anaplastic thyroid carcinoma reported was from 1 to 6 months. The terminology of the cancer in World Health Organization is "anaplastic thyroid carcinoma" rather than "undifferentiated thyroid carcinoma". In the latest American Joint Committee on Cancer (AJCC) TNM staging system for anaplastic thyroid carcinoma, there are updates on T and N categories. To conclude, updated knowledge of clinicopathological features, classification, pathological staging will improve our understanding of the cancer and will help in the management of the patients with this aggressive cancer.

Pitfalls in Thyroid Cytopathology

Fine-needle aspiration (FNA) is among the first diagnostic tools used in the evaluation of thyroid nodules. It has the ability to triage patients with benign and malignant lesions, thus defining the optimum clinical and/or surgical management. The Bethesda System for Reporting Thyroid Cytopathology has found worldwide acceptance. Thyroid FNA offers high positive predictive value (97%-99%), with sensitivities and specificities of 65% to 99% and 72% to 100%, respectively. Nonetheless, many potential diagnostic pitfalls exist that can lead to false-positive and/or false-negative results. This article discusses several of the potential pitfalls in the cytologic evaluation of thyroid lesions.

Anaplastic thyroid carcinoma with rhabdoid phenotype: An unusual case and a comprehensive review

Anaplastic thyroid carcinoma (ATC) is a highly aggressive thyroid malignancy predominantly affecting the elderly with a fatal outcome. ATC with rhabdoid phenotype is a rare variant, with only a few cases reported in the literature to date. We herein report a case of a 44-year old female diagnosed as ATC with rhabdoid phenotype. She had a slow-growing neck mass with no gross extrathyroidal extension (ETE) or nodal/distant metastasis at presentation. Computed tomography of the neck showed a well-defined heterogeneously hypodense nodule in the right lobe of the thyroid. On cytology, a diagnosis of papillary thyroid carcinoma (PTC) with possible anaplastic transformation was made based on the presence of vague papillae with focal nuclear features of PTC and atypical pleomorphic/rhabdoid cells. The total thyroidectomy specimen showed a relatively circumscribed lesion with no gross ETE. Histopathological examination revealed sheets of rhabdoid cells with a focus of poorly differentiated thyroid carcinoma. On immunohistochemistry, rhabdoid cells were positive for AE1/AE3, focally positive for PAX8 and were negative for TTF-1, synaptophysin, desmin, myogenin, S100P, and SMA. The neck lymph nodes were non-metastatic. The patient was further treated with adjuvant radioactive iodine. Four-months post-operatively, the patient developed pulmonary metastasis which on biopsy examination revealed metastatic ATC. Apart from being a rare tumor type, this case is unusual with its presentation too; wherein, unlike described earlier in the literature the patient had a relatively mitigated clinical course with no gross ETE or nodal/distant metastatic disease. We also review the relevant literature along with this case.

SMARCB1 (INI1)-deficient thyroid carcinoma: A novel entity expanding the spectrum of tumors with INI1 loss

BACKGROUND

Biallelic loss of SMARCB1/INI1 is associated with highly aggressive malignancies, namely renal and extra-renal malignant rhabdoid tumors, and atypical teratoid/ rhabdoid tumor. Increasing availability of molecular testing and immunohistochemical stains acting as surrogate tools to genetic analysis has led to an increasing recognition of SMARCB1 loss in a variety of neoplasms. Interestingly, many of these lack the typical rhabdoid features ascribed to this group of tumors, making their identification difficult.

CASE PRESENTATION

We describe the cytological, histological, immunohistochemical and molecular features of the first case of primary SMARCB1 (INI1)-deficient carcinoma of the thyroid gland in literature. The tumor was unique in various aspects; apart from never having been documented at this location, it showed extensive glandular differentiation, mimicking metastatic adenocarcinoma.

CONCLUSION

Awareness of this novel entity is essential to avoid misdiagnosis, and for appropriate management, especially in an era of increased feasibility of targeted therapy.

Cytologic features of aggressive variants of follicular-derived thyroid carcinoma

Certain carcinomas of the thyroid gland behave aggressively resulting in increased patient morbidity and poor patient prognosis. The diagnosis of these aggressive thyroid cancer subtypes is sometimes challenging and subject to increased interobserver variability. This review deals with the cytological features of such tumors including aggressive variants of papillary thyroid carcinoma, poorly differentiated thyroid carcinoma, and anaplastic thyroid carcinoma. These malignancies fall into 2 groups based on their cytomorphology: those that exhibit distinct microscopic features (eg, nuclear findings typical of classical papillary thyroid carcinoma or marked anaplasia) and those that present with more subtle cytologic features (eg, nuclear pseudostratification, "soap bubble" nuclei, supranuclear or subnuclear cytoplasmic vacuoles, rosette-like structures, hobnail cells). We review the literature regarding these aggressive thyroid cancers and highlight important phenotypic characteristics that can be useful for their diagnosis based on fine needle aspiration.

Cytological Diagnosis of an Uncommon High Grade Malignant Thyroid Tumour: A Case Report

Anaplastic Thyroid Carcinoma (ATC) is a relatively uncommon highly malignant tumour originating from the follicular cells of thyroid gland having poor prognosis. It accounts for 2% to 5% of all thyroid carcinomas and patients typically present with a rapidly growing anterior neck mass with aggressive symptoms. A 53-year-old male presented with diffuse neck swelling measuring 8x6 cm and right cervical lymph node measuring 2x2 cm since one month which was associated with dyspepsia and dyspnoea. Ultrasound and Contrast Enhanced Computed Tomography (CECT) neck revealed enlarged right lobe of thyroid and multiple enlarged cervical lymph nodes with soft tissue density nodules in bilateral lungs. Fine Needle Aspiration (FNA) from the swelling revealed giant cell, spindle cell and squamoid pattern. Focal areas showed follicular epithelial cells arranged in repeated microfollicular pattern suggesting an underlying follicular neoplasm. FNAC smears from the lymph node also revealed similar findings. Based on the cytomorphological and radiological findings, final diagnosis of ATC probably arising from underlying follicular carcinoma with cervical lymph node and lung metastasis was given. FNAC leads to prompt and definitive diagnosis, so that therapy can be initiated as soon as possible for better outcome. Multimodality therapy (surgery, external beam radiation, and chemotherapy) is the mainstay of treatment.

An Overview of the Thyroid Gland and Thyroid-Related Deaths for the Forensic Pathologist

The thyroid gland is a butterfly-shaped organ situated in the anterior neck whose functions have system-wide effects. Thyroid diseases represent some of the most commonly encountered endocrine disorders and therefore are commonly encountered at the time of autopsy. Knowing how the gland functions and the effects it may have on vital organs is important when determining the cause of death and significant contributory conditions. Endocrine-related deaths may be anatomically subtle, therefore histologic examination, review of medical records, and selected postmortem testing must be performed to correctly identify and document their presence. For this reason, it is recommended that pathologists consider regularly examining the thyroid gland histologically, particularly on decedents where no apparent anatomic cause of death is identified after the autopsy. This article provides an in-depth review of the thyroid gland, thyroid hormones, and thyroid diseases, including potential thyroid-related deaths and incidental autopsy findings.