Sonographic features of thyroid nodules that may help distinguish clinically atypical subacute thyroiditis from thyroid malignancy

Factors affecting recurrence in subacute granulomatous thyroiditis

Objective

This study aimed to evaluate the factors affecting recurrence in subacute granulomatous thyroiditis (SAT).

Methods

A total of 137 patients with SAT were enrolled in the study; 98 (71.5%) were women and 39 (28.5%) were men. The patients received either steroid or nonsteroidal anti-inflammatory drug (NSAID) for eight weeks. Erythrocyte sedimentation rate (ESR), C-reactive protein, serum thyroid-stimulating hormone (TSH), free triiodothyronine, free thyroxine (FT4), anti-thyroid peroxidase antibodies and thyroglobulin antibodies, neutrophil, lymphocyte, platelet, neutrophil to lymphocyte ratio, and platelet to lymphocyte ratio levels were evaluated. In addition, recurrence rates were compared between patients who received NSAID treatment and those who received steroid therapy.

Results

Treatment modality and pretreatment TSH, FT4, and ESR were significantly different between patients with and without recurrence (p = 0.011, 0.001, 0.004, and 0.026, respectively). Compared with patients without recurrence, those with recurrence had higher pretreatment TSH levels, but lower FT4 and ESR levels. On logistic regression analysis, treatment modality was found to be an independent risk factor for recurrence. The risk of recurrence was higher in those taking steroids than in those taking NSAIDs (p = 0.015). The optimal TSH cutoff value for recurrence was 0.045 µIU/mL, with a sensitivity of 83.3% and specificity of 76% (AUC 0.794, 95% CI 0.639-0.949).

Conclusion

The risk of SAT recurrence was higher with steroid therapy than with NSAIDs. Patients who had mild thyrotoxicosis had relatively high recurrence rate and may need a relatively longer duration of treatment.

Subacute thyroiditis presenting as a painful suspicious thyroid nodule

Summary

We report a case of subacute thyroiditis in a 40-year-old female who initially presented with painful thyroid nodules without clinical and biochemical evidence of hyperthyroidism. Thyroid ultrasound was done to evaluate the thyroid nodules and fine-needle aspiration (FNA) was performed in view of the suspicious features. As the FNA showed a follicular lesion of undetermined significance or atypia of undetermined significance (FLUS/AUS, Bethesda III), she was advised for surgical excision. She was subsequently diagnosed with subacute thyroiditis based on her clinical symptoms, biochemical evidence of hyperthyroidism, raised erythrocyte sedimentation rate (ESR) as well as low uptake on thyroid scintigraphy. The thyroid lesions disappeared after symptomatic treatment. It is important to recognise that subacute thyroiditis can present with painful thyroid lesions with ultrasound features similar to suspicious thyroid nodules which can resolve with the resolution of the thyroiditis.

Learning points

Subacute thyroiditis can present with atypical features such as the absence of pain, normal erythrocyte sedimentation rate or absence of hyperthyroidism. In subacute thyroiditis, ultrasound findings are commonly described as focal or multifocal lesions with poorly defined and heterogeneous and hypoechoic echogenicity which can be misdiagnosed as malignancy. Thyroid lesions can resolve with the resolution of thyroiditis with or without symptomatic treatment.

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.

The New Era of TIRADSs to Stratify the Risk of Malignancy of Thyroid Nodules: Strengths, Weaknesses and Pitfalls

Simple Summary

The aim of this review is to provide the reader with a comprehensive overview of thyroid imaging and reporting data systems used for thyroid nodules, so as to understand how nodules are scored with all existing systems. Both ultrasound based risk stratification systems and indications for fine-needle aspirations are described. Systems are compared by analyzing their strengths and weaknesses. Studies show satisfactory sensitivities and specificities for the diagnosis of malignancy for all systems, and none of them have shown a real significant advantage over the others in terms of raw diagnostic value. Interobserver agreement is also very similar for all systems, fairly adequate to robust. Dimensional cut-offs for fine-needle aspiration are quite similar and all RSSs seem to reduce effectively the number of unnecessary FNAs. Merging all existing systems in a common international one is desirable.

Abstract

Since 2009, thyroid imaging reporting and data systems (TI-RADS) have been playing an increasing role in the field of thyroid nodules (TN) imaging. Their common aims are to provide sonologists of varied medical specialties and clinicians with an ultrasound (US) based malignancy risk stratification score and to guide decision making of fine-needle aspiration (FNA). Schematically, all TI-RADSs scores can be classified as either pattern-based or point-based approaches. The main strengths of these systems are their ability (i) to homogenize US TN descriptions among operators, (ii) to facilitate and shorten communication on the malignancy risk of TN between sonologists and clinicians, (iii) to provide quantitative ranges of malignancy risk assessment with high sensitivity and negative predictive values, and (iv) to reduce the number of unnecessary FNAs. Their weaknesses are (i) the remaining inter-observer discrepancies and (ii) their insufficient sensitivity for the diagnosis of follicular cancers and follicular variant of papillary cancers. Most common pitfalls are degenerating shrinking nodules and confusion between individual and coalescent nodules. The benefits of all TI-RADSs far outweigh their shortcomings, explaining their rising use, but the necessity to improve and merge the different existing systems remains.

A case of nontuberculous mycobacteria-associated thyroiditis mimicking subacute thyroiditis

We describe a case of nontuberculous mycobacteria infection in the thyroid gland in a 54-year-old woman who had painful thyroid enlargement. Ultrasonography showed ill-defined hypoechoic lesions without increased vascularity in both upper lobes of the thyroid gland. Fine needle aspiration biopsy was performed, and pathology showed granulomatous inflammation with necrotic debris that the pathologist suspected was subacute granulomatous thyroiditis or tuberculosis of the thyroid gland. Nontuberculous mycobacteria infection was confirmed after right hemithyroidectomy. Antimycobacterial therapy was initiated as the treatment of choice. Nontuberculous mycobacteria in the thyroid gland appear to be rare. In clinical practice, however, it should be considered as a differential diagnosis of a painful thyroid mass. For accurate diagnosis, clinical and radiological features plus histological examination are required.

Ultrasonic Characteristics of Medullary Thyroid Carcinoma: Differential From Papillary Thyroid Carcinoma and Benign Thyroid Nodule

ABSTRACT

The aim of this study was to evaluate the differences in ultrasonic features of patients with medullary thyroid carcinoma (MTC), papillary thyroid carcinoma (PTC), and benign thyroid nodules. This study included 53 cases of MTC, 151 cases of PTC, and 200 cases of benign thyroid nodule which were pathologically confirmed. There were no significant differences in sex and thyroid gland involvement among the MTC, PTC, and benign thyroid nodule groups. The age among the 3 groups was statistically different (P = 0.002). The TNM stage of MTC was significantly higher than that of PTC (P < 0.001). Compared with PTC, the lesion size, shape, margin, echogenicity, internal nodule component, and blood flow were significantly different in MTC (P < 0.001, P < 0.001, P < 0.001, P < 0.001, P = 0.045, P < 0.001). However, there were no differences in the form of calcification and cervical lymph node involvement between the 2 groups (P = 0.671, P = 0.128). Except for the lesion size and shape (P = 0.068, P = 0.444), MTC group have significant differences in the grade of Thyroid Imaging Reporting and Data System, lesion margin, echogenicity, internal nodule component, calcification, cervical lymph node, and blood flow compared with benign thyroid nodule group (P < 0.001, P = 0.014, P = 0.032, P < 0.001, P < 0.001, P < 0.001). Our data indicate that ultrasound have important value in preoperative diagnosis of MTC. The ultrasonic features of MTC include relatively large nodules, aspect ratio less than 1, smooth edge, solid hypoechoic, microcalcification, and rich blood flow. It is necessary to combine multiple ultrasonic features for the differential diagnosis of MTC, PTC, and benign thyroid nodules.

Imaging "Thyroiditis": A Primer for Radiologists

A variety of inflammatory disorders, generically classified as "thyroiditis," can affect the thyroid gland diffusely, generating distinctive radiographic patterns. While a precise diagnosis can seldom be made based on sonographic appearance alone, interpreting these patterns in the correct clinical and biochemical context will help support the most appropriate diagnosis. We believe that the generic term "thyroiditis" is often not helpful and often may be incorrect. Therefore, it is important for radiologists to understand the sonographic and functional correlations to provide the most appropriate differential diagnosis in their reports. This brief review is designed to provide information and guidance for radiologists when dealing with various thyroid disorders which cause diffuse changes in the thyroid and underline the pitfalls most often encountered in clinical practice.

Thyroid primary and metastatic malignant tumours of poor prognosis may mimic subacute thyroiditis - time to change the diagnostic criteria: case reports and a review of the literature

BACKGROUND

The diagnosis of subacute thyroiditis (SAT) is based mainly on the presence of painful thyroid goitre and a significant increase in erythrocyte sedimentation rate (ESR). Proceeding according to these diagnostic criteria may lead to an incorrect diagnosis and treatment. Extremely dangerous is the situation when the diagnosis of SAT is erroneously made based on criteria other than ultrasound (US) image and fine needle aspiration biopsy (FNAB), which leads to delayed diagnosis of malignant tumour with poor prognosis.

CASE PRESENTATION

Five patients with typical SAT symptoms are presented. In all of them, anaplastic thyroid cancer or metastatic thyroid tumours were finally diagnosed as the cause of the initial symptoms resembling SAT. Most of the patients were initially misdiagnosed and the proper diagnosis of malignancy was delayed.

CONCLUSIONS

The authors have proposed the new diagnostic criteria for SAT, and strongly suggest that thyroid gland US should be included in the main criteria of SAT diagnosis, together with FNAB result excluding the presence of malignant tumour.

Investigation of thyroid nodules: A practical algorithm and review of guidelines

BACKGROUND

High resolution ultrasound has led to early detection of subclinical tumors and drastic increase in incidence of thyroid malignancy. To achieve a balance in appropriate investigation without perpetuating an overdiagnosis phenomenon, a concise set of evidence-based recommendations to stratify risk is required.

METHODS

We sought to assemble an evidence-based diagnostic algorithm and accompanying pictorial review for workup of thyroid nodules that summarizes the most recent guidelines. In addition, we conducted a literature search and analysis of our imaging databases.

RESULTS

Although many imaging features of benign and malignant nodules can be nonspecific, others, such as microcalcifications, lymphadenopathy, and peripheral invasion, are highly suggestive of malignancy. The predictive values of salient imaging characteristics are presented.

CONCLUSION

Evidence-based guidelines are available such that a cost-effective algorithm for thyroid nodule workup can be devised. Conservative management with a focus on periodic monitoring is the working clinical consensus on the approach to thyroid nodules.

Painful thyroid nodule, a misleading presentation of subacute thyroiditis

Typical presentation of subacute thyroiditis (SAT) is an anterior neck pain radiating up to the jaw and ear, often associated with asthenia and fever. Biology shows hyperthyroidism and inflammation. The thyroid uptake is low at scintigraphy. However, the clinical presentation of SAT may be misleading. We report two cases of SAT whose initial manifestation was a painful thyroid nodule suspected of malignancy. In both cases, ultrasound feature was a heterogeneous, hypoechoic, ill-defined area with a low vascularization on colour Doppler. These areas were interpreted by radiologist as nodules. Surgery was then considered. Such a presentation should be known by clinicians to prevent unnecessary surgery.

Subacute Thyroiditis-An Often Overlooked Sonographic Diagnosis: Report of 3 Cases

The characteristic sonographic finding of subacute thyroiditis of a heterogeneous poorly defined hypoechoic area in the thyroid gland may mimic that of thyroid malignancy. This finding needs to be interpreted in the correct clinical context to avoid an unnecessary biopsy. We describe 3 patients who underwent thyroid biopsy on the basis of suspicious sonographic findings but who subsequently had a diagnosis of subacute thyroiditis.