On a<unk>  X-ray, the<unk>  sign is a radiologic sign that suggests left lower lobe collapse. In children, however, a<unk>  sign could be normal, reflecting the shadow of the thymus. The thymic<unk>  sign or spinnaker-sail sign is due to elevation of the thymic lobes in the setting of pneumomediastinum.
Sail sign of the chest
Visakhapatnam gas leak
Matchbox sign
Juxtaphrenic peak sign
Dense artery sign
Marcus Gunn phenomenon
Shoulder pad sign
Subcutaneous emphysema