Utility of intraoperative frozen sections for thyroid nodules with prior fine needle aspiration cytology diagnosis

The Role of Frozen Section Examination in Thyroid Surgery

In endocrine pathology, frozen section (FS) examination is most commonly used for the intraoperative evaluation of thyroid and parathyroid tumors, as well as cervical lymph nodes. In the past, frozen section was considered a fundamental tool in thyroid surgery. However, with advancements in preoperative ultrasound and fine-needle aspiration biopsy (FNAB), there have been increasing queries about its routine use due to the improved preoperative diagnosis. Nowadays, while the use of FS during thyroidectomy has decreased, it is still used as an additional method for different purposes intraoperatively. FS may not always provide definitive results. If FS will alter the surgical plan or extent, it should be applied. Routine FS is not recommended for evaluating thyroid nodules. But in addition to FNAB, if FS results may change the operation plan or extent, they can be utilized. FS should not be applied for thyroid lesions smaller than 1 cm, and the entire lesion should not be frozen for FS. For the assessment of thyroid nodules, the use of FS is recommended based on the Bethesda categories of FNAB. In Bethesda I category nodules, FS may contribute to distinguishing between malignant and benign lesions and guide surgical treatment. In Bethesda II nodules, where the malignancy rate is low, the performance of FNAB and FS can be compared, but it's not recommended due to the lack of a significant contribution to the surgical strategy. The sensitivity of FS in Bethesda III and IV nodules is low; its contribution to the diagnosis is limited, and it does not provide an apparent benefit to treatment; therefore, it is not recommended. In Bethesda V nodules, FS can effectively confirm the malignancy diagnosis, contribute to the surgical strategy, and reduce the possibility of completion thyroidectomy, and accordingly, it is recommended for use. Nonetheless, in Bethesda V nodules with a benign FS report, the malignancy rate remains high, so it should not be used to rule out malignancy. In Bethesda VI nodules, the performance of FS is lower or comparable to FNAB and does not significantly contribute to the treatment strategy; hence, it is not recommended. Particularly in patients with papillary thyroid cancer, intraoperative FS can be effective in detecting extrathyroidal extension and can assist the surgeon in determining the extent of thyroid surgery and central neck dissection. FS has high sensitivity and specificity in evaluating the lymphatic status of the central region intraoperatively and can be used to determine the extent of central compartment node dissection. During thyroidectomy, FS examination can be used in recognizing parathyroid tissue and distinguishing it from fatty tissue, thymus, thyroid, lymph nodes, especially in differentiating metastatic lymph nodes.

The Use of Artificial Intelligence in the Diagnosis and Classification of Thyroid Nodules: An Update

The incidence of thyroid nodules diagnosed is increasing every year, leading to a greater risk of unnecessary procedures being performed or wrong diagnoses being made. In our paper, we present the latest knowledge on the use of artificial intelligence in diagnosing and classifying thyroid nodules. We particularly focus on the usefulness of artificial intelligence in ultrasonography for the diagnosis and characterization of pathology, as these are the two most developed fields. In our search of the latest innovations, we reviewed only the latest publications of specific types published from 2018 to 2022. We analyzed 930 papers in total, from which we selected 33 that were the most relevant to the topic of our work. In conclusion, there is great scope for the use of artificial intelligence in future thyroid nodule classification and diagnosis. In addition to the most typical uses of artificial intelligence in cancer differentiation, we identified several other novel applications of artificial intelligence during our review.

Intraoperative frozen section performance for thyroid cancer diagnosis

Objective

A primary medical relevance of thyroid nodules consists of excluding thyroid cancer, present in approximately 5% of all thyroid nodules. Fine-needle aspiration biopsy (FNAB) has a paramount role in distinguishing benign from malignant thyroid nodules due to its availability and diagnostic performance. Nevertheless, intraoperative frozen section (iFS) is still advocated as a valuable tool for surgery planning, especially for indeterminate nodules.

Methods

To compare the FNAB and iFS performances in thyroid cancer diagnosis among nodules in Bethesda Categories (BC) I to VI. The performance of FNAB and iFS tests were calculated using final histopathology results as the gold standard.

Results

In total, 316 patients were included in the analysis. Both FNAB and iFS data were available for 272 patients (86.1%). The overall malignancy rate was 30.4%% (n = 96). The FNAB sensitivity, specificity, and accuracy for benign (BC II) and malignant (BC V and VI) were 89.5%, 97.1%, and 94.1%, respectively. For all nodules evaluated, the iFS sensitivity, specificity, and accuracy were 80.9%, 100%, and 94.9%, respectively. For indeterminate nodules and follicular lesions (BC III and IV), the iFS sensitivity, specificity, and accuracy were 25%, 100%, and 88.7%, respectively. For BC I nodules, iFS had 95.2% of accuracy.

Conclusion

Our results do not support routine iFS for indeterminate nodules or follicular neoplasms (BC III and IV) due to its low sensitivity. In these categories, iFS is not sufficiently accurate to guide the intraoperative management of thyroidectomies. iFS for BC I nodules could be an option and should be specifically investigated.

Utility of intraoperative frozen sections of thyroid tissue in the age of molecular testing

OBJECTIVES

Our study aims to examine the correlation between preoperative ultrasound-guided fine-needle aspiration and intraoperative frozen section and examine the clinical benefit of frozen section in the context of the latest national guidelines on the management of differentiated thyroid cancer.

STUDY DESIGN

A retrospective review of thyroid frozen section from 2012 to2017 at one institution.

SETTING

Tertiary care centre.

PARTICIPANTS/MAIN OUTCOME

Patient demographics, fine-needle aspiration results, molecular testing results, frozen section diagnosis (classified as benign, indeterminate, or malignant), final pathologic diagnosis, initial planned surgery, actual surgery performed, need for additional surgery and complications were recorded. Complications included hematoma formation, hypocalcaemia (requiring readmission, symptomatic, or >24-hour stay post op) and recurrent or superior laryngeal nerve damage.

RESULTS

728 total patients had an intraoperative frozen section performed. A Thy 4/Bethesda V USGFNA diagnosis (n = 55) significantly correlated with a clinically important intraoperative frozen section (n = 17, P < .01). Intraoperative management was changed by the frozen section 53 times (7.2%). Molecular testing was sent on 92 USGFNA specimens, 80 of which were deemed "suspicious." Of the 49 patients whose management was upstaged intraoperatively, 29 (59%) would not necessitate a completion thyroidectomy under the latest UK and ATA guidelines based on final pathology.

CONCLUSION

Intraoperative frozen sections rarely alter the pre-surgical plan and indeed may result in expanded surgery that could have been avoided based on latest UK and US guidelines. Molecular testing of indeterminate fine-needle aspiration results does not appear to predict meaningful intraoperative frozen section results.

Targeted use of intraoperative frozen-section analysis lowers the frequency of completion thyroidectomy

BACKGROUND

The impact of intraoperative frozen section (iFS) analysis on the frequency of completion thyroidectomy for the management of thyroid carcinoma is controversial. Although specialized endocrine centres have published their respective results, there are insufficient data from primary and secondary healthcare levels. The aim of this study was to analyse the utility of iFS analysis.

METHODS

In the Prospective Evaluation Study Thyroid Surgery (PETS) 2 study, 22 011 operations for benign and malignant thyroid disease were registered prospectively in 68 European hospitals from 1 July 2010 to 31 December 2012. Group 1 consisted of 569 patients from University Medical Centre (UMC) Mainz, and group 2 comprised 21 442 patients from other PETS 2 participating hospitals. UMC Mainz exercised targeted but liberal use of iFS analysis for suspected malignant nodules. iFS analysis was compared with standard histological examination regarding the correct distinction between benign and malignant disease. The percentage of completion thyroidectomies was assessed for the participating hospitals.

RESULTS

iFS analysis was performed in 35.70 per cent of patients in group 1 versus 21.80 per cent of those in group 2 (risk ratio (RR) 1.6, 95 per cent c.i. 1.5 to 1.8; P < 0.001). Sensitivity of iFS analysis was 75.0 per cent in group 1 versus 63.50 per cent in group 2 (RR 1.2, 1.2 to 1.3; P = 0.040). Completion surgery was necessary in 8.10 per cent of patients in group 1 versus 20.8 per cent of those in group 2 (RR 0.4, 0.2 to 0.7; P = 0.001).

CONCLUSION

iFS analysis is a useful tool in determining the appropriate surgical management of thyroid disease. Targeted use of iFS was associated with a significantly higher sensitivity for the detection of malignancy, and with a significantly reduced necessity for completion surgery.

Frozen section in thyroid gland follicular neoplasms: It's high time to abandon it!

Thyroid nodules are a very common clinical condition. The 2015 American Thyroid Association (ATA) guidelines recommend surgical excision for Bethesda IV nodules. The use of intraoperative frozen section (FS) has been recommended as a strategy to tailor the extent of the initial surgery. We critically evaluated the literature that discusses the utility and cost-effectiveness of FS to make an intraoperative decision in patients with thyroid nodules classified as follicular neoplasm. FS should not be recommended as a routine intraoperative test to assess for malignancy in thyroid follicular patterned lesions due to its low performance; the high number of deferred results; the inability to adequately assess histologically defining features; the improvements in risk stratification guiding total thyroidectomy; and the low cost-effectiveness of FS.

Utility of Routine Frozen Section of Thyroid Nodules Classified as Follicular Neoplasm

OBJECTIVES

To evaluate the diagnostic performance of frozen section in thyroid nodules classified as follicular neoplasm.

METHODS

A diagnostic test meta-analysis was designed. Studies that assessed frozen section in patients with thyroid nodules and a fine-needle aspiration biopsy result of Bethesda IV were selected. The outcomes measured were the number of false- and true-positive and -negative results. We used the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) instrument for methodological quality assessment and a bivariate mixed-effects regression framework and a likelihood-based estimation of the exact binomial approach.

RESULTS

Forty-six studies from 1991 to 2018 were included. Most studies had moderate methodological quality. The overall sensitivity and specificity were 43% (95% confidence internal [CI], 0.34-0.53) and 100% (95% CI, 0.99-1.00), respectively. The hierarchic summary receiver operating characteristic curve showed an area under the curve of 0.91 (95% CI, 0.80-0.97).

CONCLUSIONS

Frozen section demonstrates moderate diagnostic performance in patients with follicular neoplasm, and its utility for making intraoperative decisions is limited. Its routine use should be discouraged.

Retrospective Study on Accuracy of Intraoperative Frozen Section Biopsy in Spinal Tumors

OBJECTIVE

Histologic types and grades are critical in the diagnosis and treatment of spinal tumors. Intraoperative frozen section is a fast and easy method in confirming pathologic diagnosis during the operation. This study was undertaken to reveal the accuracy of intraoperative frozen section biopsy in order to make proper treatment plans.

METHODS

This retrospective study concerned patients who underwent spinal tumor surgeries from 1 January, 2012 to 31 December, 2016. Frozen section biopsy and permanent biopsy were compared, and cases that had differences were counted.

RESULTS

Thirty-seven cases out of 324 patients had discrepancies (11.4%). In discrepant cases 11 cases were ependymoma (29.7%) and 6 cases were schwannoma (16.2%). Among 34 patients who were finally diagnosed with an ependymoma, 11 cases had discrepancies, which was the highest mismatch rate among tumor final pathologic types. By frozen biopsy, astrocytoma (n = 5) and ependymoma (n = 5) turned out to be the most discrepant pathologic types and 16 frozen section biopsy cases were "null." Frozen biopsy astrocytoma (n = 5) mostly turned out to be ependymoma in 4 cases.

CONCLUSIONS

Pathologic findings from frozen biopsy for spinal cord tumors could not be corresponded to final diagnosis, especially when the results of frozen biopsy were ependymoma or astrocytoma. Therefore careful decision making for treatment plans is required.