Changes in the thymus gland with age: A sonographic evaluation

Abstract

Background: Ultrasound evaluation of normal, ectopic, asymmetric, and hyperplastic thymus and also its differentiation from abnormalities are challenging in children, and few studies have addressed this issue. This study aimed to investigate the thymus sonographic changes with age. Methods: In this cross-sectional study, 118 healthy children were categorised into six age groups. Sonographic features of the thymus, including volume, anatomical position, symmetry, and echo-texture, were recorded. Results: The thymus was visible at all ages from the suprasternal view. In 77.5% of participants, the thymus gland volume in lobes was symmetrical; however, left (21.2%) and right (1.3%) predominance were also found. The most common position of the thymus was in front of the great vessels (100%) with suprasternal extension (97.5%). The mean volume of thymus was 21.3 ± 10.5 (mm). There was no significant difference in the volumes of the thymus between different age groups. The predominant echo-texture of the thymus in different age groups was hypoechoic with thin echogenic septa (liver-like) in below 2–3 years of age, the appearance of echogenic foci and hyperechoic echo-texture (liver-like with starry sky) in 2–14 years, and uniform hyperechoic echo-texture (fatty liver-like) or geographic echo-texture with coarse reticular pattern in above 14 years. Conclusion: In children, the thymus gland is visible in ultrasound examination in all age groups from the suprasternal view; however, the echo-texture of the normal thymus changes with age. There was no significant correlation between age and sex with total thymic volume. The specificity of these appearances has made ultrasound a problem-solving modality in children.