Impact of specific patterns on the sensitivity for follicular and Hurthle cell carcinoma in thyroid fine-needle aspiration

A case series of thyroid fine needle aspiration biopsies diagnosed as follicular neoplasm with oncocytic features

Oncocytic lesions of the thyroid are a heterogeneous group encompassing nonneoplastic and neoplastic entities ranging from benign to malignant and have traditionally been classified as separate entities in thyroid pathology. To illustrate the diversity of these thyroid lesions, we describe three cases of fine needle aspiration biopsies (FNAB) diagnosed as Bethesda Category IV: Follicular neoplasm, oncocytic type, under the 2017 Bethesda System for Reporting Thyroid Cytopathology (TBSRTC), with ThyroSeq v3 molecular testing and subsequent surgical excision.

Hürthle cell-predominant thyroid fine needle aspiration cytology: A four risk-factor model highly accurate in excluding malignancy and predicting neoplasm

Background

Interpretation of Hürthle cell‐predominant cytologies (HCP) is very challenging as a majority is diagnosed as indeterminate. Prior studies have reported various cytologic features to help distinguish non‐neoplastic (NN) from neoplastic and malignant lesions but had contradicting results. Our aim was to identify risk factors predictive of neoplasm and/or malignancy by correlating cytologic features with clinical and ultrasound findings.

Methods

Sixty‐nine HCP cases with surgical follow‐up were identified, including 35 NN, 20 adenomas, and 14 carcinomas. Ultrasound data were recorded utilizing Thyroid Imaging Reporting and Data System (TI‐RADS) and American Thyroid Association (ATA) scoring systems. Sixteen cytologic criteria were evaluated and semi‐quantitatively scored. Data were assessed by univariable, multivariable and stepwise logistic regression analysis; and statistical significance achieved at P‐value <0.05.

Results

On univariable analysis, significant predictors of neoplasm were high cellularity, isolated single cells, absent colloid, non‐uniform HC population (anisonucleosis), larger nodule size, and higher ATA score. Large‐cell dysplasia and transgressing blood vessels were not found to be significant factors. Multivariable analysis identified a combination of four risk factors (high cellularity, anisonucleosis, absent colloid, and size ≥2.9 cm) that was associated with neoplasm in 10/11 patients. None of 15 patients with zero or 1 out of 4 risk factors had malignancy or neoplasm on follow‐up. This model also significantly outperformed ATA and TI‐RADS scoring systems.

Conclusion

In the absence of four or three risk factors, the model excluded malignancy and neoplasm in all patients. The presence of all four factors predicted neoplasm and malignancy in 91% and 46% of cases, respectively.

Surgical indications and clinical management of benign and malignant follicular thyroid tumors: An algorithmic-based approach

The present study retrospectively reviewed the treatment courses and results of patients with follicular thyroid tumors, including carcinomas. In the 5 year study period from April 2015 to March 2020, 797 patients with differentiated thyroid carcinoma and 128 patients with follicular tumors (FTs) received surgery or treatment for distant metastases and recurrence at the Kanagawa Cancer Center (Japan). Of these patients, 73 that were diagnosed with follicular thyroid carcinoma (FTC) were included in the present study. An algorithm used for the application of treatment strategies was assessed. The aim of the present study was to examine patients with FT or FTC who were treated at the Kanagawa Cancer Center to devise appropriate treatment strategies and to evaluate the various treatment outcomes of FTC. Pre-diagnostic serum thyroglobulin and thyroid stimulating hormone levels, follow-up and overall survival (OS) were investigated in the present study. The results revealed that OS was significantly increased in patients with minimally invasive follicular thyroid cancer (MIFTC) compared with widely invasive follicular thyroid cancer (WIFTC) (log-rank test, P=0.017). Additionally, OS was significantly higher in patients without distant metastasis at the first consultation compared with those initially diagnosed with distant metastasis (log-rank test, P=0.023). Although all patients without distant metastasis at the first consultation and those with MIFTC are alive, the 10-year survival rates were 75.3% for patients with WIFTC and 75.6% for those with distant metastasis at the first consultation. The results of the present study suggested that the prognosis of WIFTC was the worst among patients with FTC and distant metastasis, and that total thyroidectomy surgery and radioactive iodine treatment are essential. Additionally, if the disease progresses, prompt inclusion of tyrosine kinase inhibitor therapy is necessary.

Hürthle cell lesions of the thyroid: Progress made and challenges remaining

Hürthle cell-predominant thyroid fine needle aspirations (FNA) are encountered frequently in routine practice, yet they are often challenging to diagnose accurately and are associated with significant interobserver variability. This is largely due to the ubiquity of Hürthle cells in thyroid pathology, ranging from nonneoplastic conditions to aggressive malignancies. Although limitations in cytomorphologic diagnoses likely will remain for the foreseeable future, our knowledge of the molecular pathogenesis of Hürthle cell neoplasia and application of molecular testing to cytologic material have increased dramatically within the past decade. This review provides context behind the challenges in diagnosis of Hürthle cell lesions and summarizes the more recent advances in diagnostic tools.

Malignancy risk for solitary and multiple nodules in Hürthle cell-predominant thyroid fine-needle aspirations: A multi-institutional study

BACKGROUND

Hürthle cell metaplasia is common in hyperplastic nodules, particularly within the setting of lymphocytic thyroiditis (LT). The Bethesda System for Reporting Thyroid Cytopathology indicates that it is acceptable to classify Hürthle cell-predominant fine-needle aspiration (HC FNA) specimens as atypia of undetermined significance (AUS) rather than suspicious for a Hürthle cell neoplasm (HUR) within the setting of multiple nodules or known LT. The goal of the current study was to address whether this approach is justified.

METHODS

HC FNA specimens were identified and correlated with ultrasound and surgical pathology reports if available. Multinodularity was determined based on findings on macroscopic examination if imaging results were unavailable.

RESULTS

A total of 698 HC FNA specimens were identified, including 576 resected nodules, 455 of which (79%) were benign. The overall risk of malignancy for HUR was 27%, whereas the risk of malignancy for AUS was 10%. The mean size of the benign nodules was 2.1 cm on surgical resection specimens, with multiple nodules noted in 293 cases (64%) and histologic LT noted in 116 cases (25%). The mean size of the malignant nodules was 2.8 cm, with multiple nodules and histologic LT noted in 74 cases (61%) and 22 cases (18%), respectively. The malignancy rate did not differ between solitary or multiple nodules (P = .52) or in the presence or absence of LT (P = .12). However, size did significantly differ between malignant and benign nodules (P < 0.01).

CONCLUSIONS

The malignancy rate did not differ significantly in the presence of multiple nodules or LT, although the latter demonstrated a statistical trend. A diagnosis of AUS over HUR based solely on the presence of multinodularity is not warranted.

Preoperative Diagnosis of Neoplastic or Malignant Hürthle Cell Lesions: A Chimera?

OBJECTIVE

We aimed to review all cytological specimens with Hürthle cells (HC) diagnosed in our institution, identify cytological features related to neoplastic (adenoma or carcinoma) and malignant histology, and discuss the role of clinicopathological findings and clinical management in these cases.

STUDY DESIGN

We included 359 thyroid fine-needle aspiration cytology cases in our study. We reviewed the clinical and cytological features of surgical cases and correlated them with histological diagnosis. We also reviewed the literature on this issue.

RESULTS

We found a significant association between neoplasia and highly cellular smears, the absence of colloid, the presence of microfollicles, large-cell dysplasia, prominent nucleoli or macronucleoli, coarse chromatin, nuclear grooves and inclusions, nuclear irregularity, and pleomorphism. The absence of colloid, high cellularity, > 25% of isolated HC, the presence of tridimensional groups, transgressing vessels, nuclear irregularity, prominent nucleoli or macronucleoli, coarse chromatin, hyperchromatism, pleomorphism, and diffuse large-cell dysplasia were features significantly associated with malignancy.

CONCLUSIONS

No cytological feature alone can predict histological outcome, but all findings related to a neoplastic or malignant histology must be assessed. Individualized management protocols should be developed in each institution.