Background/purpose: Intrathyroidal thymic tissue may be misinterpreted as a thyroid lesion in children, leading to invasive tests or resection. We sought to describe the characteristic imaging features of these lesions and to evaluate the safety of non-operative management.
Methods: A retrospective review of all patients less than 18years old with intrathyroidal thymic tissue from 2000 to 2016 was performed. Data collection included patient demographics, imaging results, interventions, and outcomes.
Results: Eleven patients were identified using institutional radiology and pathology databases. Median patient age and lesion size at presentation were 5years old (range 2 to 8years old) and 0.9cm (range 0.4 to 9.2cm), respectively. Six lesions were incidentally identified, six were left-sided, and the most common location was the lower pole. Ultrasonographic features were reproducible and included well demarcated (10/11), hypoechoic lesions (11/11), containing punctate/linear internal echoes (11/11), and occasional mild hypervascularity (6/11). All cases demonstrated interval size and echotexture stability over a median surveillance period of 3years (range 1 to 8years). While 9 patients were simply observed, the first patient in this series underwent excision, while another had a fine needle aspiration to confirm pathology.
Level of evidence: Study of diagnostic test, Level IV.
Conclusion: Intrathyroidal thymic tissue has typical clinical and sonographic characteristics which allow for appropriate diagnosis and avoids thyroid resection.
Keywords: Thymic remnant; Thyroid nodule; Ultrasonography.
Copyright © 2018. Published by Elsevier Inc.