The authors present a radiographic image portraying the “thymic sail sign” and the “thymic wave sign,” both normal findings in infant radiographs and present a short description of these signs. These are distinguished from pathologic findings such as the “spinnaker-sail sign” in pneumomediastinum.
KeywordsThymus gland Thoracic radiography
The thymic sail sign is a normal finding in infants and should not be confused with the “spinnaker-sail sign” where the thymic lobe shadow is laterally and superiorly displaced due to pneumomediastinum, as though an actual boat sail blown by strong wind . The normal thymus has a soft texture and therefore may on radiographs present an undulation of its contour caused by the ribs, known as the “thymic wave sign” (black arrows) . This appearance helps to exclude mediastinal expansive masses such as teratomas. These would not have a horizontal inferior border and may present with calcifications, whereas the normal thymus has soft tissue density.