Intrathyroidal Ectopic Thymus Research Articles

Age-related reduction of the prevalence of ectopic intrathyroidal thymus in children and its size reduction with age

Age-related reduction of the prevalence of ectopic intrathyroidal thymus in children and its size reduction with age

The Dot-and-Dash Pattern of Intrathyroidal Ectopic Thymus: Implications in the Context of TI-RADS Reporting.

The Dot-and-Dash Pattern of Intrathyroidal Ectopic Thymus: Implications in the Context of TI-RADS Reporting.

Intrathyroidal ectopic thymus: an important entity in the differential diagnosis of thyroid nodules.

Intrathyroidal ectopic thymus (IET), a benign lesion due to aberrant thymic migration during embryogenesis, is often discovered incidentally. We aimed to present the ultrasound (US) features, diagnostic methods, and follow-up of IET in children and adolescents. We searched our database of patients with a nodular thyroid lesion detected by US, between January 2007 and December 2019. In 30/255 (11.7%), IET was diagnosed. The study included 30 patients (20 males/10 females), mean age 5 years (0.1-12.2, median 5.6) with 34 lesions diagnosed by US as `incidentalomas.` None of the patients had palpable nodules. On US, IET appeared as a hypoechoic lesion, with multiple punctuate internal echoes. 29/34 of lesions had well-defined margins. The most common location of IET was in the middle part (27/34) of the left lobe (19/34). The mean longest diameter at diagnosis was 6.4 mm (2.5-21, median 4.5). Sonographic follow-up was available in 25 patients with 27 lesions. The mean time of observation was 2.7 years (0.3-7.5, median 2.1). While 13/27 cases showed decreased size or regression during follow-up, the other 13 increased in size, and there was no change in size in one. Pubertal progression was associated with both increment and decrease in size of IET. Fine needle aspiration (FNA) was performed in 5 patients and surgery in one. IET should be considered in the differential diagnosis of pediatric thyroid nodules as a cause of FNA and/or surgery. Regular US monitoring can be used safely in the follow-up of this lesion. We present one of the largest series in the literature with long-term follow-up and description of patients` pubertal status. IET prevalence was 11.7% among children and adolescents with a nodular thyroid lesion, higher than that stated in the literature.

Intrathyroidal Ectopic Thymus and Sonoelastographic Findings.

Intrathyroidal ectopic thymus (IET) can be misdiagnosed as thyroid nodules. The purpose of this study is to evaluate the sonoelastographic findings of IET in pediatric population. Twelve children who had been examined with ultrasound (US) and strain elastography between December 2012 and December 2019 were included in this retrospective study. The patients' demographics and ultrasonographic findings, including the location, margin, shape, diameters, volume, structure, vascularity, and elastography values of the lesions were evaluated. Twelve lesions were detected in 12 asymptomatic patients (3 females and 9 males) with a mean age of 4.67 ± 2.27 years. The most common location of the IET was in posterior part and middle third of thyroid, and the most common appearance on US was a well-defined, ovoid-shaped, and predominantly hypoechoic solid lesion with punctate/linear branching hyperechogenities. The lesions were mostly hypovascular on Doppler US. The mean strain ratio on elastography was found to be 1.10 ± 0.04. In the follow-up of 7 patients with available information, there was no significant change in size or appearance of IET on US. IET should be considered in the differential diagnosis of the lesions within the thyroid. The first step to accurately diagnose an IET is to consider it in the differential diagnosis. In addition to US, strain elastography findings can be used to distinguish IETs from papillary thyroid cancers which can have similar US appearance, and help avoid unnecessary biopsies.

Diagnosis and management of Intratyroid Ectopic Thymus.

Intrathyroidal ectopic thymus (IET) is a rare benign condition caused by the aberrant thymic migra tion during embryogenesis. It is usually incidentally diagnosed as a thyroid nodule. To report the intrathyroidal location of ectopic thymic tissue and to describe the ultrasound findings in children. Retrospective descriptive review of the medical charts and thyroid ultrasound studies of children with nodular images in the thyroid gland, in a third level national pediatric hospital, from January 2010 to August 2017. Solid hypoecogenic intrathyroid lesions with multiple linear tracts or hyperechogenic points that did not change their characteristics during fo llow-up were considered intrathyroidal thymos. The ultrasound follow-up was performed every 4-6 months. The ultrasound characteristics of the lesions (location, laterality, size and shape), the indi cation of the ultrasound scan and the follow-up time were analyzed. Of 147 patients with thyroid nodules, we identified 12 children with lesions suggestive of an IET (8.1%). The mean age at diagnosis was 3.9 years (range 0-8). It was an incidental finding in all cases. Imaging findings were unilateral in eight patients and bilateral in four patients. All lesions were located in the mid and/or posterior portion of the gland. We adopted a watch-and-wait approach with ultrasound follow-up (mean 2.2 years; range 0.83-4) in all patients except in a 7-year-old boy who presented uncertain findings and underwent surgery, confirming IET in the pathological study. Thymic inclu sions in the thyroid gland are a rare but increasingly frequent finding, possibly related to the increased use of ultrasound studies. Pediatricians and radiologists should be aware of this entity to differentiate it from other thyroid lesions, avoiding unnecessary studies and/or treatments in these patients.

Intrathyroidal ectopic thymus: Ultrasonographic features and differential diagnosis

Intrathyroidal ectopic thymus: Ultrasonographic features and differential diagnosis

The Role of Superb Microvascular Imaging and Shear Wave Elastography in Differentiation of Thyroid Nodules from Intrathyroidal Ectopic Thymus in Children.

Ectopic thymus could be located intrathyroidal, therefore fine ultrasound details are useful for this differentiation. To investigate differences in stiffness and vascularity properties among thyroid nodules and intrathyroidal ectopic thymus (IET) by obtaining quantitative data in children. Twenty-seven thyroid nodules and 20 IET in children were evaluated in terms of vascularity index (VI) via superb microvascular imaging (SMI) and stiffness by shear wave elastography (SWE). Differences in the volume, VI, and SWE parameters of the lesions were assessed by using the Mann-Whitney U test. Association of the age, lesion volume, SWE, and VI parameters was investigated by using Spearman's correlation analysis. The optimal cut-off values for stiffness and vascularity in the differentiation of nodules from IET were calculated with ROC analysis. The median (range) age of the participants with thyroid nodules and IET were 15.6 (10-18) years and 8.8 (3-14) years, respectively. The medians (range) VI of the IET and thyroid nodules were 4.7 (0.2-16) % and 23.8 (7.5-40)%, respectively. The median SWE values were 7.6 (4.4-9.5) kPa and 15.58 (8.5-23.4) kPa for IET and nodules, respectively. There have been highly significant differences among medians of volume, SWE, and VI values of the lesions. Significant positive correlations were found between VI and SWE parameters (p=0.001, r=0.64), and volume with VI (p=0.018, r=0.34) and SWE (p:0.001, r= 0.5). The diagnostic accuracies were 93%, 91% with the cut-off values as 9.2 kPa, 13% for the SWE and SMI, respectively. IETs were found to be less vascular and less stiff than thyroid nodules. IETs could be easily and confidently differentiated from nodules using SWE and SMI quantifications. This discrimination prompts the reduction of unnecessary interventional procedures.

Application of Shear Wave Sonoelastography in the Differential Diagnosis of Extra- and Intra-Thyroidal Ectopic Thymic Tissue.

The ultrasound (US) pattern of intrathyroidal ectopic thymus (IET) can resemble papillary thyroid carcinoma (PTC) while the extrathyroidal ectopic thymus (EET) can mimic pathological lymph nodes. Recently, the usefulness of strain elastography (SE) was demonstrated in the differential diagnosis, however this method has several limitations. The aim of the current study was to assess the usefulness of shear wave elastography (SWE) in this field. The US, SE, and SWE were performed in 31 children with 53 ectopic thymuses (ETs) and quantitative values of SWE parameters were calculated, so as to generate potential normative values of ET elasticity and of the shear wave ratio (SWR). The mean SWRIET was 0.89 ± 0.21 and the mean shear wave stiffness (SWS) was 7.47 ± 1.93 kPa. The mean SWREET was 0.84 ± 0.15 and the mean SWSEET was 11.28 ± 2.58 kPa. The results have proven that the stiffness of ETs is lower or equal to the thyroid’s. SWE was demonstrated to be a useful diagnostic method for ET evaluation. Therefore, the application of SWE in ET diagnosis allows more accurate evaluation of ET-like lesions and, in many cases, allows one to avoid invasive procedures, simultaneously providing a precise monitoring method based on combined US and SWE evaluation.

Long-term ultrasound follow-up of intrathyroidal ectopic thymus in children.

To present the sonographic follow-up of intrathyroidal ectopic thymus (IET) in children and adolescent patients. Out of the 507 children referred to FNAB between 2006 and 2018, 30 (5.9%) pediatric patients (10 females), mean age 5.7years (1.2-13.8, median 4.9years) were diagnosed with IET. A retrospective analysis of medical files of patients diagnosed with IET between 2006 and 2018. Assessed data included ultrasound characterisation, elastographic strain ratio (SR) results and hormonal evaluation. Analysis of thyroid US scans revealed that the mean age at the first thyroid ultrasound was 5.7 (1.2-13.8, median 4.9) years, and at the last US 10.7 (3.7-18, median 10.5) years. The mean time of the IET observation was 59.6 (2-148, median 53.5) months. On US, IET was hypoechoic with multiple linear and punctate echoes, hypovascular, fusiform on longitudinal plane and round or polygonal on an axial plane, more common in the right thyroid lobe (66.7%) and located in the posterior part of the lobes (54.5%), bilateral in two patients and multifocal in one patient. SR of IET was similar to the surrounding normal thyroid tissue. Complete regression of IET was observed in 12/30 patients after a mean time of 81.7months (median 76.5), at the mean age of 13.7 (9.2-18, median 13.9) years. FNAB was performed in 10/30 and a hemithyroidectomy in 1/30 IET patients. In the FNAB (+) group, patients were younger (5.08 vs 6.08years) and lesions were larger (0.12ml vs 0.05ml) than in the FNAB (-) group. All patients with IET were euthyroid with negative TPOAb and TgAb levels. The reproducibility of unique ultrasound features of IETs allows for safe long-term follow-up of these benign lesions in the majority of pediatric patients: not only monitoring the regression of IET but also screening towards the rare occurrence of a tumor arising from the IET.

Sonographic and Elastographic Features of Extra- and Intrathyroidal Ectopic Thymus Mimicking Malignancy: Differential Diagnosis in Children

Thyroid nodules with ultrasound (US) cancer risk features and extra-thyroid lesions suggesting malignant lymph nodes, require prompt diagnosis, especially in children. The US pattern of intrathyroidal ectopic thymus (IET) can strongly suggest papillary thyroid carcinoma (PTC). The extra-thyroid ectopic thymic tissue (EET) can mimic pathological lymph nodes in US. The aim of the study has been to demonstrate US features and diagnostic methods, allowing finally to confirm the presence of IET and EET in children. The US and elastographic features of 16 ectopic thymic tissue (ET) lesions were analyzed so as to describe the typical characteristics of ET and to define the best method to differentiate ET and malignant lesions. Among 16 analyzed lesions, 11 lesions were IET, and 5 were EET adjacent to the thyroid connective tissue capsule. Most of IET were located in the middle part of the right lobe and were fusiform or oval in shape. All the lesions were solid, hypoechoic, and heterogeneous with bright internal echoes. Among IET, 73% of lesions had well- or very well-defined margins. In strain elastography of IET lesions, the strain ratio was similar in all lesions, and its value ranged from 0.95 to 1.09. Despite the low prevalence of IET and cervical EET, clinicians and radiologists should be aware of US characteristics of such lesions. The confirmation of their benign character is absolutely required. Elastography is a useful tool to initially differentiate PTC and IET. However, due to high risk of malignancy in thyroid lesions in children, similarity of US features of PTC and IET, and due to the possibility of malignancy in ET, only cytological evaluation provides definitive diagnosis.

Intrathyroidal ectopic thymus tissue: a diagnostic challenge.

The prevalence of thyroid nodules in pediatric population is 0.2-2%, which is lower than adults. However, the probability of the nodule to be malignant is higher than adults (20-73%). Differential diagnosis of thyroid lesions in children includes intrathyroidal ectopic thymus tissue (ITT). ITT can present as a thyroid nodule, and be confused with malignancy with its hyperechoic pattern; this might cause unnecessary fine-needle aspiration biopsies and/or surgical interventions. In the current study, we mainly aim to define both US and color Doppler ultrasonography (CDUS) characteristics of ITT. We also aim to describe the most sensitive and most specific diagnostic parameters of ITT. We have evaluated US examination reports of 56 children for whom differential diagnosis included ITT between February 2015 and August 2018. We have recorded sonographic characteristics of the lesions, CDUS data, and thyroid hormone levels. Study population consists of 56 patients (22 ITT, 34 other diagnoses). Median age of the population is 10years. Age, sex, laboratory results, and follow-up change in lesion diameters do not show any significant difference between ITT and other diagnosis groups. Typical US appearance, fusiform lesion shape, and isovascular CDUS characteristics are higher in ITT group. The median value of the lesion's highest diameter is smaller in ITT group. The most valuable criteria to predict ITT presence were the fusiform shape and the longest diameter of the lesion. Fusiform shape and a maximum diameter of ≤ 9mm are the most selective criteria to predict ITT diagnosis.

Diagnosis of intrathyroidal ectopic thymus in thyroid fine needle aspiration samples

AimsIntrathyroidal ectopic thymus (ITET) is a rare cause of paediatric thyroid nodules. Although ultrasonography of ITET demonstrates a characteristic appearance similar to that of normal thymus, accurate differentiation from other...

Utility of monoclonal PAX8 antibody for distinguishing intrathyroid thymic carcinoma from follicular cell-derived thyroid carcinoma.

Follicular cell-derived thyroid carcinomas, including thyroid squamous cell carcinomas (SCCs) and anaplastic carcinomas, are immunoreactive for paired-box gene 8 (PAX8), while non-follicular cell-derived thyroid carcinomas stain negative for the PAX8 antibody. Intrathyroid thymic carcinoma (ITTC) arising from the intrathyroidal ectopic thymus exhibits moderate-to-strong nuclear reactivity for polyclonal PAX8. This is difficult to understand given that PAX8 is not associated with embryonic thymic development. We aimed to determine the diagnostic significance of monoclonal PAX8 antibody in distinguishing ITTCs from follicular cell-derived thyroid carcinomas. Ten ITTCs, 14 poorly differentiated thyroid carcinomas (PDTCs), 14 thyroid SCCs, 7 thymic tissue specimens, 7 thymomas, and 1 thymic carcinoma were analyzed using antibodies against polyclonal and monoclonal PAX8, thyroid transcription factor-1, p63, and CD5. Four ITTCs (40.0%) stained positive for polyclonal PAX8; none stained positive for monoclonal PAX8. All PDTCs and 92.9% of SCCs were immunoreactive for both polyclonal and monoclonal PAX8. All PDTCs, 46.2% of SCCs, and none of the ITTCs were immunoreactive for thyroid transcription factor-1. Eight ITTCs (80.0%), but none of the PDTCs and SCCs, were immunoreactive for CD5. We are the first to show that ITTCs stain negative for monoclonal PAX8. Monoclonal PAX8 is a more reliable marker than polyclonal PAX8 for determining follicular cell origin. We conclude that monoclonal PAX8 is a useful marker for distinguishing ITTCs from PDTCs and SCCs. Monoclonal PAX8 negativity is additional evidence in support of ITTCs not being follicular cell-derived thyroid carcinomas, but having a thymic origin.

Acoustic Radiation Force Impulse Imaging in the Differential Diagnosis of an Ectopic Intrathyroidal Thymus

Ectopic intrathyroidal thymus is caused by a hesitate in the migration of thymus during embryogenesis and is a rare cause of a nodular intrathyroidal lesion. Nodular thyroid lesions raise the suspicion of malignancy in the pediatric age group.

Ectopic intrathyroidal thymus in children: Prevalence, imaging findings and evolution.

Erol OB, Şahin D, Bayramoğlu Z, Yılmaz R, Akpınar YE, Ünal ÖF, Yekeler E. Ectopic intrathyroidal thymus in children: Prevalence, imaging findings and evolution. Turk J Pediatr 2017; 59: 387-394. The aim of this study was to evaluate the ultrasound (US) features of intrathyroidal ectopic thymus (IET) and demonstrate the alterations after follow-up. This study included 36 lesions of 32 patients (mean age 95 ± 58 months) diagnosed with IET. The patients underwent follow-up US examination at least 22-months without a medication or surgical intervention. A total of 36 IETs with an incidence of 0.91% were detected among 3914 thyroid ultrasound (US) examinations. The mean of anteroposterior (ap), transverse (tr), and craniocaudal (cc) diameters in the initial US examinations were 3.1±1.19 mm, 4.89±1.86 mm, and 6.45±3.92 mm respectively. All of the lesions were well-demarcated, hypoechoic to the thyroid gland, and contained uniformly distributed punctate echogenic foci. Follow-up US examinations were performed after 684±85 days. The alterations between the initial and follow-up diameters for ap and cc direction were not statistically significant. However, a significant difference (p=0.007) was found for transverse diameters and the IETs were found to be smaller at follow-up US than in the initial US. Most of the IETs were located in the left lobe (64%), middle portion (83%), and extended to a border of thyroid gland (69%) and nonspherical in shape (89%). The descriptive findings of IETs are uniform distribution of punctate echogenic foci, absence of a rim, and the presence of vessels traversing through the lesion without parenchymal displacement. Given our findings, healthcare professionals should be aware of the diagnosis of IET. Patients with an IET could be safely managed with follow-up US and any surgical treatment would not be required.

Prevalence of ectopic intrathyroidal thymus in Japan: the Fukushima health management survey.

Ectopic intrathyroidal thymus is thought to be a rare entity, often discovered incidentally, and is due to aberrant thymic migration during embryogenesis. The aim of this study was to determine the prevalence of ectopic intrathyroidal thymus in children using ultrasound screening. This study was cross-sectional and was conducted with the initial preliminary survey of the Fukushima Health Management Survey between October 9, 2011, and March 31, 2012, after the Fukushima Daiichi Nuclear Power Plant accident. A total of 37,816 children were examined in the survey. Diagnostic criteria are based on the ultrasonographic appearance of ectopic intrathyroidal thymus, which were round, oval, or polygonal hypoechoic or hyperechoic areas, with multiple granular and punctate echogenic foci. A total of 375 (0.99%) cases (164 girls) with ectopic intrathyroidal thymus were observed. The mean age was 7.0 years (range 0-18 years). Ectopic intrathyroidal thymus was located in the right (n=180), left (n=178), or bilateral (n=17) thyroid lobes. The incidence of ectopic intrathyroidal thymus was inversely correlated with age and body mass index. The results reflect the prevalence of ectopic intrathyroidal thymus using ultrasonography in the general population. Further examination will be needed by way of longitudinal follow-up.

A Case of Intratyhroidal Ectopic Thymus [Intratiroidal Ektopik Timus Olgusu

Ectopic intrathyroidal thymus tissue is rare. Mostly it is seen in childhood as an asymptomatic thyroid nodule. It can be easily misdiagnosed as a benign or malignant thyroid nodule. Like thymus, it may regress in time. Ectopic thymus tissue can rarely develop to thymoma or thymic carcinoma. Intrathyroidal ectopic thymus tissue has similar sonographic features to thymus and should be kept in mind to avoid unnecessary diagnostic and surgical intervention.

Histochemical and Morphological Characteristics of the Hassall’s Corpuscles. The Stress Affects Involution of the Ectopic Intra-Thyroidal and the Normal Position Thymus and Morphological Changes of the Hassall’s Corpuscles

We encountered three cases of the intra-thyroidal ectopic thymus at autopsy and also performed three autopsy cases consisted of mothers and children, and children with severe stress. The morphological and immune histochemical characteristics of the Hassall’s corpuscles were examined in those in ectopic and normal positioned thymus, and in the thymuses obtained from mothers and children, and children with severe stress. The Hassall’s corpuscles obtained from ectopic and normal positioned thymus showed resemble morphology and stainability with antibodies. These results indicate the Hassall’s corpuscles in the intra-thyroidal ectopic thymuses also possess the biological significance.

Intrathyroidal ectopic thymic tissue may mimic thyroid cancer: a case report

Ectopic intrathyroidal thymus tissue that may be present as a thyroid nodule is rarely reported. We present a case of a 4-year-old boy with a solitary thyroid nodule. Real-time thyroid ultrasound showed a calcified nodule in the right lobe. Complete blood count, serum calcitonin, and thyroglobulin concentration were normal and antithyroid antibodies were negative. Fine-needle aspiration (FNA) biopsy was revealed as inadequate for cytological examination. During his follow-up, nodular enlargement was found, and the patient was subjected to surgical total excision of the right lobe of the thyroid gland. Pathological examination showed an ectopic intrathyroidal thymus tissue. In childhood, ectopic intrathyroidal thymus tissue can present as an enlarging microcalcified thyroid nodule that may mimic thyroid cancer and may grow during follow-up.

Ectopic Intrathyroidal Thymus in Children: A Long-Term Follow-Up Study

Background: Ectopic intrathyroidal thymus has recently been reported in children as a cause of surgery and/or invasive diagnostic procedures when mistaken for a thyroid nodule. Thymus has a unique appearance at ultrasound (US). Methods: We report a follow-up study (mean 34 months, range 6–84) performed by US on 9 children (5 females) with a mean age of 6.3 ± 3.2 years with intrathyroidal thymic inclusions diagnosed by US as ‘incidentalomas’. None has palpable nodules. Results: Intrathyroidal thymic inclusions appeared on US as a hypoechoic area, with regular linear or punctuate internal hyperechoic echoes. The 2 oldest patients (13 and 17 years) showed a regression in both size and hypoechogenicity of thymic inclusions over time – reflecting the normal thymic involution with advancing age. Conclusions: Indeed, the lack of progression seen in our 9 patients over a mean time of 34 months confirmed the substantially benign and self-limited nature of this process. The increasing use of thyroid ultrasonography in children may result in an increased detection of intrathyroidal thymic inclusions – an embryologic anomaly that should be considered in the differential diagnosis of thyroid nodules in children and adolescents.