Prevalence of papillary thyroid cancer in subacute thyroiditis patients may be higher than it is presumed: retrospective analysis of 137 patients

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.

Charting the Unknown Association of COVID-19 with Thyroid Cancer, Focusing on Differentiated Thyroid Cancer: A Call for Caution

BACKGROUND

Conceived of as the "silver lining" of the dark cloud of the coronavirus disease 2019 (COVID-19) pandemic, lessons taught by this catastrophe should be leveraged by medical authorities and policy makers to optimize health care globally. A major lesson is that resilient health systems should absorb sudden shocks incited by overwhelming health emergencies without compromising the continuum of care of chronic diseases, especially of cancer.

METHODS

The present review dissects the association between COVID-19 and thyroid cancer (TC), especially with differentiated TC (DTC), focusing on available data, knowledge gaps, current challenges, and future perspectives.

RESULTS

Obesity has been incriminated in terms of both COVID-19 severity and a rising incidence of TC, especially of DTC. The current conceptualization of the pathophysiological landscape of COVID-19-(D)TC association implicates an interplay between obesity, inflammation, immunity, and oxidative stress. Whether COVID-19 could aggravate the health burden posed by (D)TC or vice versa has yet to be clarified. Improved understanding and harnessing of the pathophysiological landscape of the COVID-19-(D)TC association will empower a mechanism-guided, safe, evidence-based, and risk-stratified management of (D)TC in the COVID-19 era and beyond.

CONCLUSION

A multidisciplinary patient-centered decision-making will ensure high-quality (D)TC care for patients, with or without COVID-19.

Impact of Computed Tomography Scans on the Risk of Thyroid Disease in Minor Head Injury Patients: A Population-Based Retrospective Cohort Study

We investigated the association between head computed tomography (CT) scans and the risk of noncancer thyroid diseases in patients with minor head injury in a Taiwanese healthcare setting. For this retrospective population-based cohort study, the 2009–2013 Longitudinal Health Insurance Database was used to include patients with a minor head injury at admission or emergency visit between 2009 and 2013. Multivariate analysis with a multiple Cox regression model was applied to analyze the data. According to whether a CT scan was conducted within 14 days of admission, patients were divided into a CT scan group (n = 14,041) or a non-CT scan group (n = 34,684). No increased incidence of thyroid diseases was observed in the CT scan group regardless of the number of CT scans performed. The incidence rate ratio for one scan was 1.10 (95% confidence interval: 0.94–1.29) and for two or more scans was 1.09 (95% confidence interval: 0.93–1.28). In conclusion, this population-based cohort study showed that a head CT scan is not associated with increased risk of thyroid disease in patients with minor head injury. The short-term adverse effects on the thyroid could be mild when a regular CT scan is appropriately performed.

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

Subacute thyroiditis is a self-limited inflammatory disease and very few patients undergo ultrasonographic re-examination if no nodules are found at the initial examination. The objective of the study was to assess the diagnostic accuracy of ultrasonography in detecting nodular lesions in patients with subacute thyroiditis. We conducted a longitudinal study involving 710 patients with subacute thyroiditis who underwent ultrasonographic examinations in a single center between 2008 and 2018. These examinations were performed at initial diagnosis and during follow-up, with subsequent evaluation of nodules using fine needle aspiration cytology. Ultrasonographic examination used for the initial screening of thyroid nodules in patients with subacute thyroiditis showed a sensitivity of 72.4%, specificity of 89.0%, positive predictive value of 80.4%, and negative predictive value of 83.8%. Twenty-two patients (3.1%) had concomitant papillary thyroid carcinoma, 10 of whom underwent thyroidectomy while the remaining 12 opted for active surveillance owing to having low-risk microcarcinomas. Approximately 30% of papillary carcinomas (7/22) were identified during follow-up ultrasonography, but not during the initial scan. All tumors in this false-negative group were latently localized in the bilateral hypoechoic regions of the thyroid and showed no calcified components. Of the 15 tumors that were detected during both initial and follow-up examinations, 7 exhibited calcified components and 5 were located in unaffected areas apart from the inflammatory hypoechoic region. Subacute thyroiditis highly obscures any coexisting papillary carcinoma when inflammatory hypoechoic regions are present. Ultrasonographic re-examination after a sufficient interval is indispensable for patients with subacute thyroiditis.

Thyrotoxicosis with concomitant thyroid cancer

Thyrotoxicosis with concomitant thyroid cancer is rare and poorly recognized, which may result in delayed diagnosis, inappropriate treatment and even poor prognosis. To provide a comprehensive guidance for clinicians, the etiology, pathogenesis, diagnosis and treatment of this challenging setting were systematically reviewed. According to literatures available, the etiologies of thyrotoxicosis with concomitant thyroid cancer were categorized into Graves' disease with concurrent differentiated thyroid cancer (DTC) or medullary thyroid cancer, Marine-Lenhart Syndrome with coexisting DTC, Plummer's disease with concomitant DTC, amiodarone-induced thyrotoxicosis with concomitant DTC, central hyperthyroidism with coexisting DTC, hyperfunctioning metastases of DTC and others. The underlying causal mechanisms linking thyrotoxicosis and thyroid cancer were elucidated. Medical history, biochemical assessments, radioiodine uptake, anatomic and metabolic imaging and ultrasonography-guided fine-needle aspiration combined with pathological examinations were found to be critical for precise diagnosis. Surgery remains a mainstay in both tumor elimination and control of thyrotoxicosis, while anti-thyroid drugs, beta-blockers, 131I, glucocorticoids, plasmapheresis, somatostatin analogs, dopamine agonists, radiation therapy, chemotherapy and tyrosine kinase inhibitors should also be appropriately utilized as needed.