Imaging description

An asymptomatic three-week-old male infant with congenital heart disease (small atrial septal defect [ASD] and ventricular septal defect [VSD]), hypotonia, and dysmorphic facial features was admitted to the neonatal ICU for further evaluation. A portable frontal chest radiograph was obtained, which demonstrated a very prominent mediastinal shadow (Fig. 19.1a). On the left there was a clear thymic wave sign (Fig. 19.1a) but there was concern as to whether the right side was also thymus or if there was a mediastinal mass. A CT scan was ordered. The pediatric radiologist protocolling the CT reviewed the chest radiograph and suggested that this was likely normal thymus and recommended a lateral chest radiograph (Fig. 19.1b) and if necessary an ultrasound (US) study (Fig. 19.1c, d) as the more appropriate examinations to address the clinical concerns. The US examination (Fig. 19.1c, d) was still requested in spite of the reassuring appearance of the lateral chest radiograph showing that all the soft tissue prominence was anterior. The US clearly identified prominent normal thymic tissue, larger on the right than the left, extending from the thoracic inlet to the diaphragm.