Papillary thyroid carcinomas are highly obscured by inflammatory hypoechoic regions caused by subacute thyroiditis: a longitudinal evaluation of 710 patients using ultrasonography

Emerging trends and hot spots in subacute thyroiditis research from 2001 to 2022: A bibliometric analysis

BACKGROUND

Subacute thyroiditis (SAT) is the most prevalent self-limiting thyroid disease that causes pain, accounting for about 5% of all clinical thyroid disorders. Numerous clinically noteworthy results have been published in this area over the last 20 years. However, no article has comprehensively assessed the relevant literature yet. We conducted a bibliometric analysis of SAT to provide light on the dynamic nature of scientific advancement and aid researchers in gaining a global perspective while examining research core themes and hotspots.

METHODS

SAT-related articles and reviews from 2001 to 2022 were retrieved from the Science Citation Index-Expanded of Web of Science Core Collection (WoSCC). We analyzed current research trends and hotspots in this area using CiteSpace and Vosviewer.

RESULTS

A total of 568 studies associated with SAT research were published in 282 academic journals by 2,473 authors in 900 institutions from 61 countries/regions. The United States was a crucial link in inter-country/region collaboration and was the most frequently involved country in international cooperation. The University of Missouri System was the top organization, and Braley-Mullen H. was the most productive researcher. Thyroid published the most papers, with 36 publications. The most co-cited article was "Clinical features and outcome of subacute thyroiditis in an incidence cohort: Olmsted County, Minnesota, study" (by Fatourechi V., 2003). The clustered network and timeline view of keywords showed that the prevalence, diagnosis, and treatment of SAT were the research core themes during the past 20 years. Analysis of keyword bursts indicated that the clinical characteristic and the influence of COVID-19 on SAT appeared to be the current research hotspots.

CONCLUSION

This bibliometric analysis conducted a thorough review of the SAT research. The clinical characteristics and the genetic background of SAT under the influence of COVID-19 are current research hotspots. However, there is still a need for further study and global collaboration. Our findings can aid researchers in understanding the current status of SAT research and immediately pinpoint new directions for further investigation.

Subacute thyroiditis paranchime heterogeneity may mask thyroid nodules and higher EU-TIRADS scores

PURPOSE

Nonhomogenous and ill-defined hypoechoic areas are typical ultrasonographic features of subacute thyroiditis (SAT). Evaluating a thyroid nodule accurately in this heterogeneous paranchime may be troublesome. This study aims to compare thyroid nodules, their characteristics, and European Thyroid Imaging and Reporting Data System (EU-TIRADS) categories at the time of the diagnosis and in the remission of SAT.

METHODS

Ultrasonographic features of SAT and characteristics and EU-TIRADS categories of thyroid nodules in the initial and control ultrasonography (US) of 350 patients with SAT have been evaluated in this retrospective observational study. Fine needle aspiration biopsy (FNAB) results and postsurgical data, if performed, have been estimated.

RESULTS

A hundred patients (28.6%) with SAT had thyroid nodules at the time of the diagnosis, while 152 (43.4%) patients had a nodule in remission US (p < 0.001). The number of thyroid nodules was found to be higher in the control US as against the initial US (p = 0.001). EU-TIRADS scores of the nodules in the remission US were significantly higher than the scores at the time of the diagnosis (p < 0.001). FNAB was performed in 23% of nodules observed in the remission US, and the rate of thyroid carcinoma within them was 3.3%.

CONCLUSION

Thyroid nodules, malignancy suspected features, and EU-TIRADS categories of them may not be appropriately evaluated due to heterogenous paranchime of SAT. Performing a control US examination after resolution of hypoechoic areas may be beneficial to avoid missing clinically significant nodules with high EU-TIRADS scores.

New aspects in the pathogenesis and management of subacute thyroiditis

Subacute thyroiditis (SAT) is a thyroid inflammatory disease, whose pathogenesis and determinants of the clinical course were unclear for many decades. The last few years have brought many clinically significant new data on the epidemiology, pathogenesis and management of SAT. Several human leukocyte antigen (HLA) alleles were demonstrated not only to increase the risk of SAT, but also to correlate with SAT clinical course and determine the risk of recurrence. The world-wide epidemic of the coronavirus disease 19 (COVID-19) has provided new observations that the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) can be a potent SAT-triggering factor, and that the clinical course of SAT in patients affected by COVID-19 is different from a typical one. Additionally, many new trends in the clinical course are emerging. In the last years, painless course of SAT is more and more often described, constituting a special challenge in patients hospitalized due to COVID-19. Despite an excellent availability of diagnostic methods, several difficulties in SAT differential diagnosis can be currently encountered and the proper diagnosis and treatment is frequently delayed. False positive diagnoses of SAT in patients with malignancies of poor prognosis constitute a life-threatening problem. Taking into account all the new aspects of SAT pathogenesis and of its clinical course, the new - modified - SAT diagnosis criteria have been proposed.

Value of Contrast-Enhanced Ultrasound in Differentiating Clinically Atypical Subacute Thyroiditis from Papillary Thyroid Carcinomas

Our objective was to provide the various sonographic characteristics of clinically atypical subacute thyroiditis (CAST) in distinguishing CAST from papillary thyroid carcinomas (PTCs) by using conventional ultrasound (US) and contrast-enhanced ultrasound (CEUS). Forty-six CAST patients and 50 PTC patients were enrolled in this study. We evaluated the size, shape, margin, echogenicity, calcification, vascularity and CEUS parameters for each nodule. The final diagnosis of CAST was confirmed via fine-needle aspiration (FNA) or surgery. Of the 46 CASTs, 13 (28.3%) were confirmed by surgery to be benign, and 33 (71.7%) were proven by FNA to be benign. Univariate analysis indicated that compared with PTCs, CAST lesions more frequently had wider-than-taller shapes, blurred margins, the absence of microcalcifications, peripheral high echogenicity, the absence of internal vascularity, hypo-enhancement, centrifugal perfusion and a peak intensity index <1 and area under the curve index <1 on pre-operative US and CEUS. A multivariate analysis revealed that clear margins, microcalcifications and centripetal perfusion were independent characteristics related to PTCs for their differentiation from CAST (all p values <0.05). Our study indicated that the pre-operative multiparameter US characteristics may serve as a useful tool for distinguishing CAST from malignant thyroid nodules to avoid surgical excisions or unnecessary FNAs.

Ultrasound in active surveillance for low-risk papillary thyroid cancer: imaging considerations in case selection and disease surveillance

Active surveillance (AS) of small, low-risk papillary thyroid cancers (PTCs) is increasingly studied in prospective observational studies. Ultrasound is the primary imaging modality for case selection. While researchers have put forward selection criteria for PTCs based on size, absence of suspicious lymph nodes and tumor location, there are limited reported data highlighting inherent ultrasound limitations and guidelines for case selection and follow-up. We report our experience including imaging limitations encountered in the ongoing AS prospective observational study for PTCs measuring < 2 cm at our institute. We define disease progression as an increase in size of > 3 mm in the largest dimension of nodule or evidence of metastatic disease or extrathyroidal extension. Accurate, consistent and reproducible measurements of PTCs are essential in risk stratifying patients for the option of AS or disease progression. Interobserver discrepancy, shadowing from coarse calcification and background parenchyma heterogeneity or thyroiditis can limit accurate PTC size assessment and therefore hinder patient eligibility evaluation or AS follow-up. Following the ACR Thyroid Imaging, Reporting and Data System (TI-RADS) protocol of three-axes technique to measure a thyroid nodule enables reproducibility of measurements. In patients with multi-nodular goiter, accurate identification and labeling of the PTC is important to avoid mistaking with adjacent benign nodules at follow-up. Ultrasound assessment for extrathyroid extension of PTC, and relationship of PTC to trachea and the anatomic course of the recurrent laryngeal nerve are important considerations in evaluation for AS eligibility.

COVID-19-related thyroiditis: A novel disease entity?

The literature on COVID-19-related thyroid complications has accumulated over the past year or so as the pandemic has accelerated throughout the world. In particular, several recent case reports have been published describing a possible correlation between COVID-19 disease and subacute thyroiditis (SAT). In this review, we briefly present one of our own patients and review the current published literature in this area up to January 2021, including analyses of major series of thyroid function tests in patients with significant COVID-19 infection. We conclude that while the great majority of patients with severe COVID-19 infection may show manifestations of the sick euthyroid syndrome, clinicians should be aware of the possibility of SAT, especially in the early weeks and months following even mild COVID-19 infection.