Anaplastic Thyroid Carcinoma: Cytomorphologic Features on Fine-Needle Aspiration and Associated Diagnostic Challenges

Anaplastic thyroid cancer: Genetic roles, targeted therapy, and immunotherapy

Anaplastic thyroid cancer (ATC) stands as the most formidable form of thyroid malignancy, presenting a persistent challenge in clinical management. Recent years have witnessed a gradual unveiling of the intricate genetic underpinnings governing ATC through next-generation sequencing. The emergence of this genetic landscape has paved the way for the exploration of targeted therapies and immunotherapies in clinical trials. Despite these strides, the precise mechanisms governing ATC pathogenesis and the identification of efficacious treatments demand further investigation. Our comprehensive review stems from an extensive literature search focusing on the genetic implications, notably the pivotal MAPK and PI3K-AKT-mTOR signaling pathways, along with targeted therapies and immunotherapies in ATC. Moreover, we screen and summarize the advances and challenges in the current diagnostic approaches for ATC, including the invasive tissue sampling represented by fine needle aspiration and core needle biopsy, immunohistochemistry, and 18F-fluorodeoxyglucose positron emission tomography/computed tomography. We also investigate enormous studies on the prognosis of ATC and outline independent prognostic factors for future clinical assessment and therapy for ATC. By synthesizing this literature, we aim to encapsulate the evolving landscape of ATC oncology, potentially shedding light on novel pathogenic mechanisms and avenues for therapeutic exploration.

Insights into Thyroid and Salivary Gland Cytopathology: Highlights from a 45th European Congress of Cytology Slide Seminar

INTRODUCTION

Thyroid and salivary gland cytopathology frequently present diagnostic challenges due to complex presentations, overlapping features between benign and malignant conditions, particularly with gray-zone entities and rare pathologies. To address these issues, the 45th European Congress of Cytology (ECC) held a slide seminar focused on challenging cases. This article reviews key findings from the 6 cases discussed, emphasizing the importance of a comprehensive diagnostic approach. The objective of this article was to illustrate the diagnostic challenges of rare thyroid and salivary gland lesions through case presentations, showing the need for a comprehensive, multidisciplinary approach to accurately reach a final diagnosis and steer the patient's management.

CASE PRESENTATION

The seminar presented cases involving fine-needle aspiration cytology followed by histopathological correlation, molecular and cytogenetic analyses or immunohistochemistry (IHC) markers to elucidate cytomorphological features, differential diagnoses, and final diagnoses of rare cases in thyroid and salivary gland cytopathology. Challenging thyroid cytology cases included differentiating thyroid sarcoidosis from malignancy, identifying intrathyroidal ectopic thymus versus lymphoid neoplasms, and recognizing poorly differentiated thyroid carcinoma initially misinterpreted as a benign follicular neoplasm. Complex salivary gland cases addressed the distinction of basal cell adenocarcinoma from adenoid cystic carcinoma, metastatic SMARCB1-deficient carcinoma diagnosed via IHC and a parotid mass initially identified as a Warthin tumor.

CONCLUSION

These cases highlight the critical role of integrating cytological, clinical, and histopathological data to navigate the diagnostic complexities of thyroid and salivary gland lesions. A multidisciplinary approach and standardized algorithms are essential for improving diagnostic accuracy and patient outcomes.

Advanced Unresectable Differentiated Thyroid Cancer With Anaplastic Transformation: A Case Report and Review of the Literature

Papillary thyroid carcinoma (PTC) is the most common subtype of thyroid cancer (TC). Although surgery and radioactive iodine therapy (RAI) generally yield favorable outcomes, advanced cases with extensive local invasion and metastases pose significant challenges. We report the case of a 65-year-old male with advanced, inoperable PTC characterized by extensive local invasion and distant metastases. A whole-body radioiodine scan revealed no iodine-avid disease. However, following recombinant human thyrotropin (rhTSH) preparation, the patient developed severe compressive symptoms, necessitating glucocorticoid treatment. Lenvatinib monotherapy was initiated, resulting in initial symptom relief. Unfortunately, the disease rapidly progressed due to anaplastic transformation of the PTC, ultimately leading to the patient's death. This report highlights the challenges of managing advanced differentiated TC (DTC) and the risk of aggressive transformation into anaplastic TC (ATC), even with targeted therapy. It underscores the critical need for close monitoring and a multidisciplinary approach. Further research is needed to explore the role of targeted therapies, such as lenvatinib, in altering tumor biology and their long-term effects on disease progression.

Non-papillary thyroid carcinoma diagnoses in The Bethesda System for Reporting Thyroid Cytopathology categories V and VI: An institutional experience

BACKGROUND

The non-papillary thyroid carcinoma (PTC) subgroups of The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) categories V (Suspicious for malignancy) and VI (Malignant) are rare, and specific tumor typing is difficult. We aimed to analyze histologic outcomes and to investigate the points of caution.

METHODS

We reviewed the electronic database and identified 12,215 cases of thyroid fine-needle aspiration cytology between 2013 and 2022. In total, 2783 patients were diagnosed with TBSRTC V or VI. Of these, 51 patients with non-PTC diagnosis were identified. Histological outcomes were analyzed with the cytologic findings.

RESULTS

The subgroups of non-PTC diagnoses in TBSRTC category V or VI consisted of medullary thyroid carcinoma (MTC) (13/51, 25.5 %), anaplastic thyroid carcinoma (3/51, 5.9 %), lymphoma (2/51, 3.9 %), metastatic tumor (4/51, 7.8 %), and malignant, not otherwise specified (NOS) (29/51, 56.9 %). The concordance rate of the histological outcomes was 30 % (12/40), predominantly comprising MTC cases. The obscuring factors for specific tumor typing in the suspicious for malignancy/malignant NOS cytology diagnosis group was mixed pattern of well differentiated thyroid carcinoma and less differentiated carcinoma cells (9/24, 37.5 %), low cellularity (7/24, 29.2 %) and a history of non-thyroid organ malignancy (6/24, 25 %). The less differentiated carcinoma component in mixed pattern consisted of 2 poorly differentiated thyroid carcinomas, 2 anaplastic thyroid carcinomas, 4 high-grade PTCs and 1 high-grade MTC.

CONCLUSION

The high-grade feature of PTC or MTC cytology is a noteworthy obscuring factor in specific tumor typing of non-PTC cytology diagnosis.

Identification of novel characteristic biomarkers and immune infiltration profile for the anaplastic thyroid cancer via machine learning algorithms

PURPOSE

Anaplastic thyroid cancer (ATC) is a rare and lethal malignant cancer. In recent years, the application of molecular-driven targeted therapy and immunotherapy has markedly improved the prognosis of ATC. This study aimed to identify characteristic genes for ATC diagnosis and revealed the role of ATC characteristic genes in drug sensitivity and immune cell infiltration.

METHODS

We downloaded ATC RNA-sequencing data from the GEO database. Following the combination and normalization of the dataset, we first divided the combined datasets into the training cohort and the validation cohort. We identified differentially expressed genes (DEGs) in ATC by differential expression analysis in the training cohort. We used two machine learning algorithms, least absolute shrinkage and selection operator (LASSO) and support vector machine-recursive feature elimination (SVM-RFE) to identify ATC characteristic genes. The CIBERSORT algorithm was performed to calculate the abundance of various immune cells in ATC. Finally, we validated the expression of ATC characteristic genes by quantitative RT-PCR (RT-qPCR) in ATC cell lines and immunohistochemistry (IHC).

RESULTS

A total of 425 DEGs were identified in the training cohort, including 240 upregulated genes and 185 downregulated genes. Four ATC characteristic genes (ADM, PXDN, MMP1, and TFF3) were identified, and their diagnostic value was validated in the validation cohort (AUC in ROC analysis > 0.75). We established a practical gene expression-based nomogram to accurately predict the probability of ATC. We also found that ATC characteristic biomarkers are associated with the tumor immune microenvironment and drug sensitivity.

CONCLUSION

ADM, PXDN, MMP1, and TFF3 might serve as potential ATC diagnostic biomarkers and may be helpful for ATC molecular targeted therapy and immunotherapy.