Variants of Papillary Thyroid Carcinoma: An Algorithmic Cytomorphology-Based Approach to Cytology Specimens

Can Aggressive Papillary Thyroid Carcinoma Variants With Oncocytıc Morphology (Tall Cell and Hobnail Variants) be Detected Cytologically? Is the Differentiation as Straightforward as Reported?

OBJECTIVE

Identifying aggressive variants of throid papillary carcinoma correctly is paramount, as their diagnosis requires more extensive surgical interventions. Numerous cytologic scoring systems have been proposed to distinguish non-aggressive from aggressive variants. Oncocytic morphology is characterised by cells with abundant granular cytoplasm resulting from mitochondrial accumulation. This feature is particularly prominent in specific PTC variants. Tall cell and hobnail variants are aggressive variants with oncocytic morphology. The present study aims to evaluate the cytomorphological features of 51 histologically confirmed papillary thyroid carcinoma (PTC) cases with oncocytic morphology and to identify cytological features that could facilitate the distinction between aggressive (tall cell and hobnail) and non-aggressive (oncocytic and Warthin-like) variants during the FNA stage, thereby enabling early detection of aggressive variants.

METHODS

We retrospectively examined the cytological features of cases diagnosed with histologically confirmed aggressive variants with poor prognosis (tall cell and hobnail) and non-aggressive variants with good prognosis (oncocytic and Warthin-like), obtained from the pathology department of our hospital between 2014 and 2020.

RESULTS

39 cases (76.5%) classified into the good prognosis group, which included oncocytic variant (O-PTC) (33 cases) and Warthin-like variant (WL-PTC) (6 cases). The poor prognosis group included 12 cases (23.5%), comprising hobnail variant (HN-PTC) (2 cases) and tall cell variant (TC-PTC) (10 cases). The swirl pattern was significantly more frequent in the poor prognosis group (83.3% vs. 43.6%, p = 0.022), with a sensitivity of 83.3% and specificity of 56.4%. The presence of nuclear grooves was observed in all cases of the poor prognosis group (100%) while in 61.5% of the good prognosis group (p = 0.011). This feature exhibited 100% sensitivity and 38.4% specificity. Concerning cytoplasmic volume, scant-medium amount cytoplasmic volume was significantly more common in the poor prognosis group (66.7% vs. 20.5%, p = 0.005), showing 66.7% sensitivity and 79.4% specificity, and yielding the highest accuracy rate (76.4%) among all characteristics.

CONCLUSIONS

Oncocytic morphology-based approaches may help identify poor prognosis variants and guide clinical decisions. In our study, cellular swirls, grooves and scant-medium cytoplasmic volume were the most significant cytological indicators for identifying poor prognosis variants. Despite previous emphasis on cell width/height ratio and foamy INCIs for TC-PTC diagnosis, no significant differences were found between the two groups in our study.

Cytologic hallmarks and differential diagnosis of papillary thyroid carcinoma subtypes

Papillary thyroid carcinoma (PTC) is the most common thyroid malignancy, characterized by a range of subtypes that differ in their cytologic features, clinical behavior, and prognosis. Accurate cytologic evaluation of PTC using fine-needle aspiration is essential but can be challenging due to the morphologic diversity among subtypes. This review focuses on the distinct cytologic characteristics of various PTC subtypes, including the classic type, follicular variant, tall cell, columnar cell, hobnail, diffuse sclerosing, Warthin-like, solid/trabecular, and oncocytic PTCs. Each subtype demonstrates unique nuclear features, architectural patterns, and background elements essential for diagnosis and differentiation from other thyroid lesions. Recognizing these distinct cytologic patterns is essential for identifying aggressive subtypes like tall cell, hobnail, and columnar cell PTCs, which have a higher risk of recurrence, metastasis, and poorer clinical outcomes. Additionally, rare subtypes such as diffuse sclerosing and Warthin-like PTCs present unique cytologic profiles that must be carefully interpreted to avoid diagnostic errors. The review also highlights the cytologic indicators of lymph node metastasis and high-grade features, such as differentiated high-grade thyroid carcinoma. The integration of molecular testing can further refine subtype diagnosis by identifying specific genetic mutations. A thorough understanding of these subtype-specific cytologic features and molecular profiles is vital for accurate diagnosis, risk stratification, and personalized management of PTC patients. Future improvements in diagnostic techniques and standardization are needed to enhance cytologic evaluation and clinical decision-making in thyroid cancer.

Prediction of classical versus non classical papillary thyroid carcinoma subtypes from cytology of nodules classified according to TIRADS

PURPOSE

Our purposes were: 1) to estimate the prediction performance (PP) of cytology in identifying papillary thyroid carcinoma (PTC) subtypes; 2) to explore how the PTC subtypes distribute among the American College of Radiology (ACR) Thyroid Imaging Reporting and Data System (TI-RADS) categories.

METHODS

Nodules were included if both the histology with the PTC subtype report and the cytology report with the possible PTC subtype were available. The PP was calculated by making the proportion of True positives/False positives+false negatives.

RESULTS

309 cytologically "suspicious for malignancy" and "malignant" thyroid nodules with PTC histology were evaluated. ACR TI-RADS categorization for classical PTC was significantly different from non-classical PTC (p-value 0.02). For the whole cohort the PP of cytologically classical cases was 0.74, while that of cytologically non classical cases was 0.41. ACR TI-RADS categorization was not significantly different for aggressive vs non-aggressive PTC subtypes (p-value 0.1). When considering only aggressive or non-aggressive PTC subtypes, the PP of cytologically classical cases was respectively 0.86 and 0.87, while that of cytologically non classical cases was respectively 0.27 and 0.22. The PP of cytologically classical cases was 0.73 and 0.79, respectively for macroPTCs and microPTCs, while that of cytologically non classical cases was 0.55 and 0.33, respectively for macroPTCs and microPTCs.

CONCLUSION

Cytology examination reliably performed in predicting classical PTC versus non classical PTC subtypes. ACR TI-RADS categorization was significantly different among classical PTC versus non classical PTC subtypes.

An Algorithmic Approach to Defining Variants of Papillary Thyroid Carcinoma: Accuracy of Fine Needle Aspiration Cytology

Introduction

Among thyroid malignancies, papillary thyroid carcinoma (PTC) is the most common, with the classical variant being the most common subtype. Some histological variants have aggressive behavior, advanced presentation stages, poor clinical outcomes, and may require additional therapy. Due to overlapping cytologic features and heterogeneity of lesions, the PTC classification is not adhered to in conventional reporting practice. This study aimed to classify the PTC cytology cases into a particular cytological variant by applying an algorithmic approach and correlating these variants with histology.

Materials and Methods

An analysis of all histopathologically confirmed cases of PTC who had previously been diagnosed with fine needle aspiration cytology (FNAC) from January 2014 to December 2019 was conducted. FNAC samples of thyroid nodules were blindly reviewed and classified into different morphological variants using a stepwise algorithmic approach based on architectural, nuclear, and cytoplasmic features.

Results

A review of 77 histologically proven cases of PTC variants or with a predominant area of variant histomorphology was done. One case was inadequate (TBSRTC I), nine cases were benign (TBSRTC II), two were follicular lesions of undetermined significance (TBSRTC III), and 65 cases were suspicious or definite for PTC (TBSRTC V/VI). Retrospective algorithmic cytopathological analysis of 65 cases that are suspicious or definite of PTC (TBSRTC V/VI) showed classical PTC (5), follicular variant-PTC (35), tall cell variant (20), diffuse sclerosing variant (1), warthin-like variant (2), and solid variant (2). Diagnostic accuracy of cytopathology in diagnosing the PTC variants when compared with histopathological diagnosis varied from 81.3% to 100% (mean 78.9%). Cluster analysis justified that our classification showed good agreement with the actual classification based on the cytopathological features identified by the cluster analysis.

Conclusion

An awareness of cytomorphological features of aggressive variants may facilitate early and accurate diagnosis and appropriate clinical management with better patient outcomes. FNAC can subclassify PTC into different variants based on this algorithmic approach or aggressive and nonaggressive variants based on certain more frequently observed features.

Do Histologically Aggressive Subtypes of Papillary Thyroid Microcarcinoma have Worse Clinical Outcome than Non-Aggressive Papillary Thyroid Microcarcinoma Subtypes? A Multicenter Cohort Study

Histologically aggressive micropapillary thyroid carcinomas (PTMC) subtypes are thought to be associated with an aggressive clinical course. However, evidence for unfavorable clinical outcomes in patients with aggressive PTMC subtypes is not clear. In this study, we intended to determine the difference in clinical outcomes between patients with aggressive and non-aggressive PTMC subtypes. In this multicenter cohort study, the computer-recorded clinical and histopathological data of patients who underwent thyroid surgery between January 2000 - January 2021 in 9 referral centers and were diagnosed as PTMC were analyzed. A total of 1585 patients [female 1340 (84.5%), male 245 (15.5%), mean age 47.9±11.63 years), with a mean follow-up time of 66.55±37.16 months], were included in the study. Ninety-eight cases were diagnosed as aggressive and 1487 as non-aggressive subtypes. Persistent/recurrent disease was observed in 33 (33.7% )and 41 (2.8%) patients with aggressive and non-aggressive subtypes (p<0.001). Diseases-free survival rates were markedly lower in patients with aggressive than in those with non-aggressive PTMC subtypes (66.3 vs. 94.8%, log-rank p<0.001). Moreover, in multivariate analysis, aggressive histology was an independent predictor of persistent/recurrent disease, after controlling for other contributing factors (HR 5.78, 95% CI 3.32-10, p<0.001). Patients with aggressive PTMC subtypes had higher rates of incomplete biochemical and structural response than patients with non-aggressive subtypes as well (p<0.001). Aggressive PTMC subtypes share many characteristics with histologically identical tumors>1 cm in size. Therefore, the histopathological subtype of PTMC should be taken into consideration to tailor a personalized management plan.

TAGLN2 promotes papillary thyroid carcinoma invasion via the Rap1/PI3K/AKT axis

TAGLN2, an actin-binding protein, functions as a binding protein to actin to facilitate the formation of intracellular cytoskeleton structures. TAGLN2 overexpression in papillary thyroid carcinoma (PTC) is reported in our previous study. This study aimed to examine the functions and molecular mechanisms of TAGLN2 in PTC. The clinical data analysis showed that TAGLN2 expression was associated with cervical lymph node metastasis in PTC. Gain- and loss-of-function approaches, as well as various cellular function, gene expression profiles, quantitative proteomics, and molecular biology experiments, were further exploited to explore the roles of TAGLN2 in PTC. The results showed that TAGLN2 overexpression significantly promoted the invasion of PTC cell lines (K1, TPC-1, and BCPAP). Besides, the results also indicated that TAGLN2 was associated with regulating proliferation, migration, angiogenesis, and adhesion of PTC cells. Gene expression profile, quantitative proteomics, and Western blotting were performed to identify the relevant pathways and key downstream molecules, and Rap1/PI3K/AKT signalling pathway, ITGB5, LAMC2, CRKL, vimentin, N-cadherin, and E-cadherin were finally focused on. Moreover, rescue experiments validated the involvement of the Rap1/PI3K/AKT signalling pathway in the TAGLN2-mediated invasion of PTC cells. Therefore, TAGLN2 may promote the invasion of PTC cells via the Rap1/PI3K/AKT signalling pathway and may be served as a potential therapeutic target for PTC. Developing antagonists targeting TAGLN2 may be a potentially effective therapeutic strategy for PTC.

Breast metastasis of papillary thyroid carcinoma

Papillary thyroid carcinoma (PTC) is the most common type of thyroid cancer, and regional neck metastasis is more common than distant metastasis. If present, metastasis most frequently occurs in lungs and bones. Follicular variant of papillary thyroid carcinoma (FVPTC) is a mixture of the classic and follicular thyroid carcinoma and metastasizes in the same fashion as the PTC with cervical lymph nodes as the most common site. A case of atypical presentation of FVPTC with rib metastasis is reported. We present a case of an old man with a left-sided palpable breast mass for 2 months in duration without breast pain. Initially, the breast mass was categorised as Breast Imaging Reporting and Data System (BI-RADS) 4a via ultrasonography. Subsequent immunohistochemistry demonstrated that the mass was metastatic thyroid cancer. Consequently, a CT scan revealed a tumour originating from the rib. The patient was finally diagnosed with metastatic FVPTC.

Diagnostic Value of Serum lncRNA HOTAIR Combined with Galectin-3 in Benign and Papillary Thyroid Carcinoma

Purpose

Papillary thyroid carcinoma (PTC) is the most common type of thyroid cancer. LncRNA HOTAIR (HOx Transcript AntIsense RNA) and Galectin-3 are involved in PTC. This study explored the clinical effect of lncRNA HOTAIR/Galectin-3 on PTC patients.

Methods

Subjects were assigned into PTC (160 cases) and benign thyroid tumor groups (150 cases). Fasting peripheral venous blood was collected. LncRNA HOTAIR/Galectin-3 expressions in serum were detected. Subjects were assigned into HOTAIR/Glactin-3 high/low expression groups and their correlation with age, gender, BMI, tumor size, pathological stage, TSH, TPO-Ab, and TG-Ab in PTC was analyzed. Receiver operating characteristic (ROC) curve was conducted on diagnostic efficacy of HOTAIR or/and Galectin-3. The difference of area under the curve (AUC) was compared and analyzed.

Results

HOTAIR and Glactin-3 were higher in PTC group and correlated with tumor pathological stage. Higher HOTAIR/Glactin-3 expression indicated a more advanced TNM stage. LncRNA HOTAIR was positively correlated with TPO-Ab and TG-Ab. AUC of HOTAIR for PTC diagnosis was 0.895, with 96.00% specificity and 80.63% sensitivity. AUC of Glactin-3 for PTC diagnosis was 0.817, with 66.67% specificity and 78.75% sensitivity. AUC of HOTAIR combining with Glactin-3 for PTC diagnosis was 0.969 with 96.00% specificity and 87.50% sensitivity. AUC of lncRNA HOTAIR was higher than that of Glactin-3, while AUC of the combination was higher than that of lncRNA HOTAIR or Glactin-3.

Conclusion

LncRNA HOTAIR and Glactin-3 were highly expressed in PTC. The combination detection of lncRNA HOTAIR/Glactin-3 had higher diagnostic efficiency on the differential diagnosis of benign thyroid tumor and PTC.

Challenges in Cytology Specimens With Hürthle Cells

In fine-needle aspirations (FNA) of thyroid, Hürthle cells can be found in a broad spectrum of lesions, ranging from non-neoplastic conditions to aggressive malignant tumors. Recognize them morphologically, frequently represents a challenging for an adequately diagnosis and are associated with a significant interobserver variability. Although the limitations of the morphologic diagnosis still exist, the interpretation of the context where the cells appear and the recent advances in the molecular knowledge of Hürthle cells tumors are contributing for a more precise diagnosis. This review aims to describe the cytology aspects of all Hürthle cells neoplastic and non-neoplastic thyroid lesions, focusing on the differential diagnosis and reporting according to The Bethesda System for Reporting Thyroid Cytology (TBSRTC). New entities according to the latest World Health Organization (WHO) classification are included, as well as an update of the current molecular data.

[Limitation of possibilities of cytological diagnosis of papillary thyroid cancer at the pre-surgery stage]

AIM OF STUDY

A comparison of papillary cancer variants diagnosed on the basis of cytological findings of pre-surgery puncture biopsies with a histological variant of papillary cancer.

MATERIALS AND METHODS

The findings of two experts specializing in cytological diagnostics of thyroid nodules that diagnosed a possible variant of papillary cancer were compared with histological findings based on the study of material from surgically removed neoplasms.

RESULTS

It was shown that the cytological examination at the pre-surgery stage has significant limitations in diagnosing the histological variant of the tumor, despite high sensitivity of method in diagnosing papillary cancer in general. The variability of results of the cytological determination of papillary cancer variant between the two experts was not so significant, it concerned small fluctuations in the frequency of the diagnosing og normal, follicular, cystic and Uortino-like variants. Based on the data of cytological method, it is not possible to establish the encapsulated variant and papillary microcarcinoma; there are limitations in the diagnosis of follicular and high tumor cell variants.

CONCLUSIONS

Currently, the advisability of the recommendation to determine the variant of papillary cancer using the cytological method is questionable. However, this does not mean that it is necessary to stop the search for reliable cellular and molecular genetic characteristics of clinically aggressive variants of papillary cancer.