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Long-term ultrasound follow-up of intrathyroidal ectopic thymus in children
D Januś1,2, A Kalicka-Kasperczyk3,4, M Wójcik3,4
1Department of Paediatric and Adolescent Endocrinology, Chair of Paediatrics, Institute of Paediatrics, Jagiellonian University Medical College, Wielicka St. 265, 30-663, Kraków, Poland. dominika.janus@uj.edu.pl.
Insights
Intrathyroidal ectopic thymus (IET) in children can be safely monitored with ultrasound. Most cases show regression over time, reducing the need for invasive procedures.
Area of Science:
- Pediatric Endocrinology
- Diagnostic Imaging
- Head and Neck Surgery
Background:
- Intrathyroidal ectopic thymus (IET) is a rare condition in pediatric patients.
- Accurate diagnosis and monitoring are crucial for appropriate management.
- Ultrasound is a key imaging modality for evaluating thyroid abnormalities in children.
Purpose of the Study:
- To describe the sonographic characteristics and follow-up of intrathyroidal ectopic thymus (IET) in pediatric patients.
- To assess the natural history, including regression, of IET.
- To evaluate the role of ultrasound in differentiating IET from other thyroid lesions.
Main Methods:
- Retrospective analysis of 30 pediatric patients diagnosed with IET between 2006 and 2018.
- Detailed assessment of ultrasound features, including echogenicity, vascularity, and shape.
- Correlation of ultrasound findings with elastography (strain ratio) and hormonal evaluation.
Main Results:
- IET presented as hypoechoic lesions with specific echo patterns, typically in the posterior thyroid lobe.
- Complete regression of IET was observed in 40% of patients within a mean follow-up of 59.6 months.
- Ultrasound features were reproducible, and elastography showed similar strain ratios to normal thyroid tissue.
Conclusions:
- Ultrasound is a reliable tool for the long-term follow-up of pediatric IET.
- The benign nature of IET allows for conservative management with monitoring for regression.
- Long-term surveillance can also help detect rare instances of tumor development within IET.
Objective:
To present the sonographic follow-up of intrathyroidal ectopic thymus (IET) in children and adolescent patients.
Patients:
Out of the 507 children referred to FNAB between 2006 and 2018, 30 (5.9%) pediatric patients (10 females), mean age 5.7 years (1.2-13.8, median 4.9 years) were diagnosed with IET.
Methods:
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.
Results:
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 81.7 months (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 6.08 years) and lesions were larger (0.12 ml vs 0.05 ml) than in the FNAB (-) group. All patients with IET were euthyroid with negative TPOAb and TgAb levels.
Conclusion:
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.
