Asymmetric diffuse thyroid uptake on 18F-FDG PET/CT in patient with subacute thyroiditis: Case report and literature review.

A 48-year-old man with an intermittent fever of 39.0oC for more than three weeks underwent computed tomography (CT) and blood testing, which revealed no clues. Antibiotics wereadministered, but his condition did not improve. Fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) showed right-lobe-dominant diffuse thyroid uptake. On technetium-99m (99mTc) pertechnetate scintigraphy, the thyroid gland could not be visualized, and he was diagnosed with subacute thyroiditis (SAT). When asymmetric 18F-FDG diffuse thyroid uptake on PET/CT is observed in a patient with a fever of unknown origin (FUO), SAT may need to be considered.

A Rare Case of Painless Destructive Thyroiditis Resulting in Thyroid Storm.

Thyroid storm is a life-threatening clinical condition that is usually triggered by untreated or interrupted treatment of Graves' disease, leading to the sudden onset of severe thyrotoxicosis, which requires an immediate diagnosis and treatment based on diagnostic criteria. Cases of thyroid storm caused by painless/painless subacute thyroiditis are very rare. We herein report an 85-year-old man with features of severe thyrotoxicosis caused by painless/painless subacute thyroiditis who had no uptake of 99mTcO4 and was negative for thyroid-stimulating hormone receptor antibodies. In thyroid storm patients in whom the findings are inconsistent with Graves' disease, careful follow-up and management are necessary, assuming the possibility of painless or painless subacute thyroiditis.

Ultrasound-Guided Capsular Thyroid Injection Therapy With Dexamethasone and Lidocaine Mixture for Subacute Thyroiditis: A Single-Center Study.

OBJECTIVES: Subacute thyroiditis (SAT) is a self-limiting, inflammatory thyroid disease possibly caused by viral infection. In recent years, the incidence of SAT is increasing, especially during the pandemic of the COVID-19. This study aimed to evaluate the efficacy, safety, and recovery time of capsular thyroid injection therapy under ultrasound guidance for SAT. METHODS: A total of 73 patients with SAT were divided into two groups. Patients in group A (n = 48) received an ultrasound-guided capsular injection consisting of dexamethasone (DEX) and lidocaine in the thyroid lesion area, while patients in group B (n = 25) received oral prednisolone (PSL). The two groups were compared for pain relief and treatment duration, the recovery time of thyroid function, recurrence rates, hypothyroidism incidence, and drug-related side effects. RESULTS: The follow-up time was 1 year. In group A, the duration of pain relief, treatment, and recovery time of thyroid function were significantly shorter than that in group B (P < .05), and no statistically significant differences in recurrence rate or incidence of hypothyroidism were observed (P > .05). Weight gain was significantly higher in group A at the end of treatment (P < .001). CONCLUSIONS: Compared with oral PSL treatment, ultrasound-guided local injection of DEX and lidocaine into the capsular thyroid is a safe and effective procedure that can significantly reduce the treatment time of SAT.

Diagnostic Value of Color Doppler Ultrasonography in Subacute Thyroiditis.

In order to explore the clinical effect of color Doppler ultrasonography in the diagnosis of subacute thyroiditis, a method for the diagnosis of subacute thyroiditis by color Doppler ultrasonography was proposed. From November 2019 to November 2020, 90 patients with subacute thyroiditis in our hospital were selected as the experimental group; 90 healthy people were selected as the control group during the same period. Both groups were diagnosed by color Doppler ultrasonography and compared. The experimental results showed that patients with subacute thyroiditis showed mild to moderate enlargement of the involved thyroid gland, and local or diffuse inhomogeneous hypoechoic areas may appear in bilateral or unilateral thyroid glands: irregular edges, unclear boundaries, no "ball feel," mottled changes, and accompanied by tenderness. The blood flow signal around the hypoechoic area is rich, and the internal blood flow signal is less. There was no significant increase in the blood flow velocity of the superior thyroid artery on the affected side. Color Doppler ultrasound not only is simple, economical, and non-invasive but also has a good diagnostic accuracy for subacute thyroiditis, which can provide an important basis for clinical diagnosis and treatment and is worthy of popularization and application.

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.

Thyroid Scintigraphy of a Rare Case of Left Thyroid Lobe Hemiagenesis With Subacute Thyroiditis.

ABSTRACT: Thyroid hemiagenesis is a rare developmental anomaly. Patients with thyroid hemiagenesis have higher incidence of coexisting thyroid disorders in the remaining lobe. We present a rare case of a 21-year-old woman with subclinical hyperthyroidism incidentally found to have thyroid hemiagenesis on thyroid 123I-Na scan, which is confirmed on thyroid ultrasound. On scintigraphy, only the right lobe showed activity. Thyroid ultrasound demonstrated that the right lobe was normal without any nodule. The left lobe was not visualized. This patient's thyroid uptake and scan also revealed low uptake in the remaining right thyroid lobe in keeping with subacute thyroiditis.

Subacute thyroiditis associated with COVID-19.

We report a case of a hospitalised patient with COVID-19 who developed subacute thyroiditis in association with SARS-COV-2 infection. The patient presented with tachycardia, anterior neck pain and thyroid function tests revealing hyperthyroidism together with consistent ultrasonographic evidence suggesting subacute thyroiditis. Treatment with corticosteroids resulted in rapid clinical resolution. This case illustrates that subacute thyroiditis associated with viruses such as SARS-CoV-2 should be recognised as a complication of COVID-19 and considered as a differential diagnosis when infected patients present with tachycardia without evidence of progression of COVID-19 illness.

The contribution of ultrasonographic findings to the prognosis of subacute thyroiditis.

OBJECTIVE: Ultrasound assessment plays an important role in the diagnosis, and monitoring of subacute thyroiditis (SAT). However, the relationship between ultrasonographic findings and severity or prognosis of the disease is not known. The aim of the present study was to evaluate the relationship between bilateral and unilateral disease involvement and severity and prognosis of the disease. SUBJECTS AND METHODS: The initial laboratory values, ultrasonographic findings and long-term outcomes of 247 SAT patients were evaluated retrospectively. RESULTS: In the ultrasonographic evaluation, bilateral involvement was detected in 154 patients, and unilateral involvement in 93 patients at the time of diagnosis. No significant difference was found between patients with bilateral or unilateral disease at the time of diagnosis in respect of the initial acute phase reactants. FT4 was significantly higher and TSH was significantly lower in the group with bilateral disease. Bilobar or unilobar disease on ultrasound at the time of diagnosis was not found to be a risk factor for permanent hypothyroidism or recurrence. The mean thyroid volume was determined to be 22.5 ± 10 cm3 at the beginning of treatment, and 11.2 ± 8 cm3 at the end of treatment. The initial thyroid volume and the thyroid volume at the end of treatment were significantly lower in patients who developed hypothyroidism. CONCLUSION: There was no relationship between initial acute phase reactants and bilateral or unilateral involvement of the disease. FT4 levels were found to be associated with the extension of the disease. The risk of recurrence and permanent hypothyroidism are not associated with the initial ultrasonographic aspect. Arch Endocrinol Metab. 2020;64(3):306-11.

The contribution of ultrasonographic findings to the prognosis of subacute thyroiditis

ABSTRACT Objective Ultrasound assessment plays an important role in the diagnosis, and monitoring of subacute thyroiditis (SAT). However, the relationship between ultrasonographic findings and severity or prognosis of the disease is not known. The aim of the present study was to evaluate the relationship between bilateral and unilateral disease involvement and severity and prognosis of the disease. Subjects and methods The initial laboratory values, ultrasonographic findings and long-term outcomes of 247 SAT patients were evaluated retrospectively. Results In the ultrasonographic evaluation, bilateral involvement was detected in 154 patients, and unilateral involvement in 93 patients at the time of diagnosis. No significant difference was found between patients with bilateral or unilateral disease at the time of diagnosis in respect of the initial acute phase reactants. FT4 was significantly higher and TSH was significantly lower in the group with bilateral disease. Bilobar or unilobar disease on ultrasound at the time of diagnosis was not found to be a risk factor for permanent hypothyroidism or recurrence. The mean thyroid volume was determined to be 22.5 ± 10 cm3 at the beginning of treatment, and 11.2 ± 8 cm3 at the end of treatment. The initial thyroid volume and the thyroid volume at the end of treatment were significantly lower in patients who developed hypothyroidism. Conclusion There was no relationship between initial acute phase reactants and bilateral or unilateral involvement of the disease. FT4 levels were found to be associated with the extension of the disease. The risk of recurrence and permanent hypothyroidism are not associated with the initial ultrasonographic aspect. Arch Endocrinol Metab. 2020;64(3):306-11

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.

Female Patient with Simultaneous Occurrence of Subacute Thyroiditis and Focal Autonomy.

A 57-year-old female patient presented at the emergency department with fatigue, increased sweating, flushing symptoms, loss of appetite, drowsiness and severe diarrhea. Besides she also mentioned painful left-sided sore throat radiating to the temples, beginning two weeks after a flu and subfebrile temperatures.

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.

18F-FDG PET/CT imaging of atypical subacute thyroiditis in thyrotoxicosis: A case report.

BACKGROUND: In addition to its established role in oncologic imaging, F-fluorodeoxyglucose positron emission tomography/computed tomography (F-FDG PET/CT) is useful for the assessment of inflammatory activity. However, subacute thyroiditis (SAT) in thyrotoxicosis is rarely detected during these scans. CASE: A 66-year-old man with SAT in thyrotoxicosis demonstrated symptoms of transient fatigue, headache, and fever, without typical neck pain. Using F-FDG PET/CT, we found increased F-FDG uptake in the thyroid gland, predominantly in the right side due to SAT. We also observed a coexisting decrease in F-FDG uptake in the liver and increased F-FDG uptake in skeletal muscle due to thyrotoxicosis. CONCLUSION: Using F-FDG PET/CT, the combined observations of increased F-FDG uptake in the thyroid and skeletal muscle, and decreased F-FDG uptake in the liver, even when the typical symptom of neck pain is subtle or absent, may be helpful for the differential diagnosis of SAT in thyrotoxicosis.

Risk Stratification of Thyroid Nodules With Atypia of Undetermined Significance/Follicular Lesion of Undetermined Significance (AUS/FLUS) Cytology Using Ultrasonography Patterns Defined by the 2015 ATA Guidelines.

PURPOSE: The purpose of this study was to evaluate the predictive value of ultrasonography (US) patterns based on the 2015 American Thyroid Association (ATA) guidelines for malignancy in atypia of undetermined significance or follicular lesion of undetermined significance (AUS/FLUS) nodules. METHODS: From January 2014 to August 2015, 133 thyroid nodules that were initially diagnosed as AUS/FLUS on fine needle aspiration (FNA) were included in this study. Each nodule was assigned a category with US patterns defined by the ATA guidelines. Clinical characteristics and US patterns were compared between the benign and malignant nodules, and malignancy rates were calculated according to the ATA guidelines. RESULTS: The malignancy rate in the very low suspicion group was 0.0% in AUS/FLUS nodules. When applying the ATA guidelines, significant differences existed for US patterns between the benign and malignant nodules in the AUS group ( P = .032) but not the FLUS group ( P = .168). CONCLUSIONS: Ultrasonography patterns by the 2015 ATA guidelines can provide risk stratification for nodules with AUS cytology but not for ones with FLUS cytology. For nodules with AUS/FLUS cytology with the very low suspicion pattern of the ATA guidelines, follow-up US might be recommended instead of repeat FNA.

Lesson of the month 1: Subacute thyroiditis: a rare cause of fever of unknown origin.

Fever of unknown origin (FUO) is sometimes a diagnostic dilemma for clinicians. Endocrine causes reported in the literature include subacute thyroiditis, thyrotoxicosis, adrenal insufficiency and pheochromocytoma. Among these, subacute thyroiditis is often overlooked as it can occasionally lack typical symptoms. This case illustrates the fact that subacute thyroiditis should be considered as a possible cause of fever even if signs and symptoms of hyperthyroidism and thyroid tenderness are absent.

Sonographic Characteristics and Interval Changes of Subacute Thyroiditis.

OBJECTIVES: This study aimed to assess the sonographic characteristics and interval changes of subacute thyroiditis using follow-up sonography. METHODS: From January 2008 to December 2014, 85 patients with clinically suspected subacute thyroiditis underwent sonographic examinations by a single radiologist. Subacute thyroiditis was confirmed on the basis of the clinical, sonographic, and cytohistopathologic findings. On the initial and follow-up sonograms, the individual sonographic findings and interval changes were retrospectively investigated by the same radiologist. According to the sonographic configuration, subacute thyroiditis lesions were categorized as nodular or non-nodular. The interval changes in the lesions were classified as follows: "disappeared," "decreased," "increased," "eventually smaller," "eventually larger," or "no interval change." RESULTS: Subacute thyroiditis was confirmed in 64 of the 85 patients. In these 64 patients, nodular (n = 39) and non-nodular (n = 35) lesions were found; 10 patients had both nodular and non-nodular lesions. Of the 64 patients, 41 underwent sonographic follow-up. In both nodular and non-nodular lesions, the common interval changes included disappeared, decreased, and eventually smaller patterns. Although the increased pattern was found only in 4 nodular lesions, there was no significant difference in the interval changes between nodular and non-nodular lesions. On follow-up sonography, a new lesion was detected in 6 patients. CONCLUSIONS: The prevalence rate of nodular subacute thyroiditis lesions on sonography was high, and the interval changes in the lesions were variable.