The KWAK TI‐RADS and 2015 ATA guidelines for medullary thyroid carcinoma: Combined with cell block‐assisted ultrasound‐guided thyroid fine‐needle aspiration

Abstract

Objective: To compare the value of the thyroid imaging reporting and data system proposed by Kwak (KWAK TI-RADS) and the 2015 American Thyroid Association (ATA) guidelines for diagnosis of medullary thyroid carcinoma (MTC) and papillary thyroid carcinoma (PTC). To confirm the role of cell block (CB)-assisted fine-needle aspiration (FNA) in final diagnosis of MTC. Design: Retrospective hospital-based cohort study. Patients: Ninety-three patients with 29 MTCs, 31 PTCs and 33 thyroid adenomas (TAs) who underwent thyroidectomy from January 2010 to May 2019 were retrospectively reviewed. The KWAK TI-RADS and ATA guidelines were used to assess each thyroid nodule. FNA, CB-assisted FNA and core needle biopsy (CNB) were performed in final diagnosis. Results: Age and ultrasound features (composition, echogenicity and shape) were significantly different between MTC and PTC. Sex and ultrasound features (echogenicity, margin and calcification) were significantly different between MTC and TA.The KWAK TI-RADS and ATA guidelines showed no significant difference for MTC (area under the curve [AUC]: 0.812 and 0.808; P = .37-.85) or PTC (AUC: 0.883 and 0.885; P = .25-.96). The KWAK TI-RADS and ATA guidelines showed high specificity and sensitivity for MTC (93.9% and 62.1%, 87.9% and 65.5%) and PTC (93.9% and 67.7%, 87.9% and 77.4%), respectively. For suspicious MTC (7 cases), CB-assisted FNA provide accuracy preoperative diagnosis. Conclusions:Although the diagnostic performance of the TI-RADS and ATA guidelines is worse for MTC than PTC, the difference is not statistically significant. CBassisted FNA should be performed in thyroid nodules with 4a or lower suspicion to avoid misdiagnosis of MTC. K E Y W O R D S 2015 American Thyroid Association management guideline, medullary thyroid carcinoma, papillary thyroid carcinoma, thyroid imaging reporting and data system, ultrasound | 451 LI et aL. How to cite this article: Li J, Li H, Yang Y, Zhang X, Qian L. The KWAK TI-RADS and 2015 ATA guidelines for medullary thyroid carcinoma: Combined with cell block-assisted ultrasound-guided thyroid fine-needle aspiration. Clin Endocrinol (Oxf). 2020;92:450-460. https ://doi.

Commentary on the study of Li J et al: The KWAK TI‐RADS and 2015 ATA guidelines for medullary thyroid carcinoma, combined with cell block‐assisted ultrasound‐guided thyroid fine‐needle aspiration

“…However, it is important to stress that this observation requires validation in further prospective and multicentre studies. Hence, to avoid misdiagnosis of MTC, I agree with the conclusion of Li et al, that cell block‐assisted FNA cytology should be performed in thyroid nodules that fall into the 4a category or low suspicion category in KWAK TI‐RADS and the ATA guidelines, respectively …”

“…The Li retrospective study of 29 patients with MTC, 31 patients with PTC and 33 patients with follicular adenoma treated in a single centre from 2000 to 2019 focused on the clinical usefulness of the recent Thyroid Imaging Reporting and Data System proposed by Kwak et al (KWAK TI‐RADS) and 2015 ATA guidelines with the combination of cell block‐assisted and ultrasound‐guided FNA for the improved diagnosis accuracy of MTC, a novel approach previously not tested . The Li study demonstrated that certain ultrasonographic features were more common in (and therefore suggestive of) MTC than PTC . It is well known that MTC and PTC may have some overlapping sonographic features of malignancy, but in this Chinese study, MTC had some sonographic features that differed from PTC, including tumour composition (mixed cystic and solid component), echogenicity (homogeneously isoechoic or markedly hypoechoic) and shape (more rounder shape).…”

Usefulness of Serum Calcitonin in Patients with Thyroid Nodules ≤ 1 cm Without an Indication for Fine-Needle Aspiration

“…Approximately 95 % of MTC correspond to nodules with an intermediate or high suspicion sonographic pattern according to the ATA classification or to nodules categories 4 and 5 of TI-RADS [12][13][14][15]. FNA is recommended for non-autonomous nodules > 1 cm with this ultrasonographic appearance.…”

“…Finally, only patients who had nodules with two or more suspicious features (solid or predominantly solid, hypoechogenicity, microcalcifications, irregular margins, anteroposterior diameter larger than transverse diameter) were included. Using this criterion, the nodules would currently be classified as intermediate or high suspicion by ATA or TI-RADS 4 or 5 [12][13][14][15].…”

“…Considering that approximately 95 % of MTC correspond to nodules defined as intermediate or high suspicion by the sonographic classification of the American Thyroid Association (ATA) or as category 4 or 5 of the Thyroid Imaging, Reporting and Data System (TI-RADS) [12][13][14][15], the lack of diagnosis of microMTC would be a matter of concern primarily in the case of thus classified nodules measuring ≤ 1 cm.…”