Purpose or Case Report: The pediatric thymus is a constant but confusing, dynamic entity. The goal of this educational exhibit is to illustrate the range of appearances of the normal thymus and to identify key imaging features that can help pediatric radiologists differentiate normal thymic tissue from neoplastic conditions and other mimics.
Methods & Materials: We retrospectively collected cases of varied appearances of the normal thymus across different modalities and patient ages, including normal thymic variants, ectopic thymic tissue, and non-neoplastic thymic conditions such as rebound hyperplasia. Imaging modalities included ultrasound, CT, and MRI. Clinical data, operative reports, and pathology reports were correlated with imaging findings.
Results: A pictorial review of varied appearances of the normal thymus will be presented. Cases will include absence of the thymus in a fetal MRI in a fetus with diGeorge syndrome, ectopic thymic tissue in the neck, ectopic thymic tissue in the supraclavicular region, and rebound thymic hyperplasia. The characteristic imaging features of the thymus will be reviewed across different modalities. We will also review the embryology, anatomy, and dynamic physiology of the thymus.
Conclusions: After reviewing this exhibit, the reader will become familiarized with varied imaging appearances of the pediatric thymus across different modalities, patient ages, and various clinical situations. Recognizing the varied appearances of the thymus is essential to avoid unnecessary imaging or invasive procedures.