Reevaluating diagnostic categories and associated malignancy risks in thyroid core needle biopsy

A simplified four-tier classification for thyroid core needle biopsy

PURPOSE

To propose a simplified histological classification for core-needle biopsy (CNB) of thyroid nodules with four diagnostic categories (DC) and provide the risk of malignancy (ROM) and the expected incidence for each DC. There is no uniform scheme for categorizing CNB specimens, except for a Korean diagnostic classification similar to the Bethesda system for FNAC.

METHODS

Data from a single institution using CNB as a routine diagnostic tool for thyroid nodules. Biopsies were classified as non-diagnostic, benign, follicular tumour (FT) or malignant. The frequency of each DC and the correlation with surgical pathology of nodules undergoing surgery after CNB were evaluated.

RESULTS

Of 6284 CNBs on 5782 nodules [195 (3.1%) non-diagnostic, 5043 (80.3%) benign, 435 (6.9%) FT and 611 (9.7%) malignant], 1914 nodules (33.1%) underwent surgery after 2016 CNBs: 48 non-diagnostic, 1035 benign, 355 FT and 578 malignant. Malignancy was diagnosed after surgery in 11 non-diagnostic (ROM: 22.9%), 23 benign (ROM: 2.2%), 44 FT (ROM: 12.4%, 11.5% excluding low-grade malignancy) and 568 malignant CNBs (ROM: 98.3%, 93.8% excluding low-grade malignancy). Sensitivity and positive predictive value for malignancy of FT or malignant CNB were 94.7% and 65.6%, and for thyroid neoplasm (adenoma or carcinoma) were 93.2% and 92.6%.

CONCLUSIONS

Our diagnostic classification for CNB of thyroid nodules has a high diagnostic accuracy with a low rate of indeterminate categories. This classification, applied in a Western practice, shows a low ROM for nodules classified as follicular tumours, which could be improved with immunohistochemical studies.

Educational exchange in thyroid core needle biopsy diagnosis: enhancing pathological interpretation through guideline integration and peer learning

BACKGROUND

While fine needle aspiration cytology (FNAC) plays an essential role in the screening of thyroid nodules, core needle biopsy (CNB) acts as an alternative method to address FNAC limitations. However, diagnosing thyroid CNB samples can be challenging due to variations in background and levels of experience. Effective training is indispensable to mitigate this challenge. We aim to evaluate the impact of an educational program on improving the accuracy of CNB diagnostics.

METHODS

The 2-week observational program included a host mentor pathologist with extensive experience and a visiting pathologist. The CNB classification by The Practice Guidelines Committee of the Korean Thyroid Association was used for the report. Two rounds of reviewing the case were carried out, and the level of agreement between the reviewers was analyzed.

RESULTS

The first-round assessment showed a concordance between two pathologists for 247 thyroid CNB specimens by 84.2%, with a kappa coefficient of 0.74 (indicating substantial agreement). This finding was attributed to the discordance in the use of categories III and V. After peer learning, the two pathologists evaluated 30 new cases, which showed an overall improvement in the level of agreement. The percentage of agreement between pathologists on thyroid CNB diagnosis was 86.7%, as measured by kappa coefficient of 0.80.

CONCLUSIONS

This educational program, consisting of guided mentorship and peer learning, can substantially enhance the diagnostic accuracy of thyroid CNB. It is useful in promoting consistent diagnostic standards and contributes to the ongoing development of global pathology practices.

Core needle biopsy for thyroid nodules assessment-a new horizon?

Ultrasound-guided fine-needle aspiration is the standard for evaluating thyroid nodules with a high safety profile and a relatively low number of non-diagnostic cytological findings. Nevertheless, this diagnostic method traditionally has its weak points. Several diagnostic categories such as Bethesda I, III and IV are not reliable for thyroid carcinoma risk assessment. Recent advancements in a core needle biopsy made it possible to use this tool as a new method for thyroid nodules evaluation. The main feature of this method is the use of thin needles (18-21G) and guns with an automatic trigger mechanism. The histological material collected with the use of a core needle biopsy is usually superior to cytological. Therefore, the core needle biopsy can be used as a complementary technique to a standard fine needle aspiration in difficult and dubious cases of thyroid neoplasia with uncertain malignant potential.

Diagnostic implication of thyroid spherules for cytological diagnosis of thyroid nodules

OBJECTIVE

Thyroid fine-needle aspiration (FNA) is a principal diagnostic procedure for thyroid nodules. A specific cytomorphological structure, known as the thyroid spherule, is often seen in FNA specimens. The clinical significance of these spherules in terms of diagnosis and prevalence remains largely unexplored.

METHODS

We performed a retrospective study on 310 thyroid FNA specimens and categorized them according to the Bethesda System for Reporting Thyroid Cytopathology. The presence, size and number of thyroid spherules in each specimen were examined and these data were subsequently correlated with the clinicopathological features.

RESULTS

Thyroid spherules were almost exclusively detected in benign cases, comprising 7.6% of all benign diagnoses. The average diameter of spherules in benign cases was 84.9 μm. Benign cases and cases with atypia of undetermined significance cases primarily exhibited low cellularity, while follicular neoplasms and malignant cases typically showed moderate to high cellularity. In the subgroup of FNA cases with moderate to high cellularity, spherules were identified in 12 (20%) of 59 benign FNA cases. Within this group, the sensitivity and specificity of thyroid spherules for detecting benign FNA cases were 20% and 100%, respectively.

CONCLUSIONS

Our results suggest that the presence of thyroid spherules in FNA specimens can serve as a highly specific marker for benign thyroid conditions. The prevalence of spherule detection is strongly influenced by the cellularity. In cases with moderate to high cellularity, the identification of spherules can assist the cytopathologists in diagnosing thyroid FNA cases as benign.

The Diagnostic Role of Repeated Biopsy of Thyroid Nodules with Atypia of Undetermined Significance with Architectural Atypia on Core-Needle Biopsy

BACKGRUOUND

We aimed to evaluate the utility of repeat biopsy of thyroid nodules classified as atypia of undetermined significance with architectural atypia (IIIB) on core-needle biopsy (CNB).

METHODS

This retrospective study evaluated patients with thyroid nodules categorized as IIIB on CNB between 2013 and 2015. Demographic characteristics, subsequent biopsy results, and ultrasound (US) images were evaluated. The malignancy rates of nodules according to number of CNBs and the number of IIIB diagnoses was compared. Demographic and US features were evaluated to determine factors predictive of malignancy.

RESULTS

Of 1,003 IIIB nodules on CNB, the final diagnosis was determined for 328 (32.7%) nodules, with 121 of them confirmed as malignant, resulting in a malignancy rate of 36.9% (95% confidence interval, 31.7% to 42.1%). Repeat CNB was performed in 248 nodules (24.7%), with 75 (30.2%), 131 (52.8%), 13 (5.2%), 26 (10.5%), one (0.4%), and two (0.8%) reclassified into categories II, IIIB, IIIA, IV, V, and VI, respectively. Malignancy rates were not significantly affected by the number of CNBs (P=0.291) or the number of IIIB diagnoses (P=0.473). None of the nodules confirmed as category II on repeat CNB was malignant. US features significantly associated with malignancy (P<0.003) included solid composition, irregular margins, microcalcifications, and high suspicion on the US risk stratification system.

CONCLUSION

Repeat biopsy of nodules diagnosed with IIIB on CNB did not increase the detection of malignancy but can potentially reduce unnecessary surgery. Repeat biopsy should be performed selectively, with US features guiding the choice between repeat biopsy and diagnostic surgery.

A Narrative Review of the 2023 Korean Thyroid Association Management Guideline for Patients with Thyroid Nodules

The 2023 Korean Thyroid Association (KTA) Management Guideline for Patients with Thyroid Nodules constitute an update of the 2016 KTA guideline for thyroid nodules and cancers that focuses specifically on nodules. The 2023 guideline aim to offer updated guidance based on new evidence that reflects the changes in clinical practice since the 2016 KTA guideline. To update the 2023 guideline, a comprehensive literature search was conducted from January 2022 to May 2022. The literature search included studies, reviews, and other evidence involving human subjects that were published in English in MEDLINE (PubMed), Embase, and other relevant databases. Additional significant clinical trials and research studies published up to April 2023 were also reviewed. The limitations of the current evidence are discussed, and suggestions for areas in need of further research are identified. The purpose of this review is to provide a summary of the 2023 KTA guideline for the management of thyroid nodules released in May 2023 and to give a balanced insight with comparison of recent guidelines from other societies.