X-ray chest PA showing mesocardia and L-posed aorta in levo transposition of great arteries (L-TGA)
Important differential diagnosis for a shadow along the left upper cardiac border are:
1. L – posed aorta (ascending aorta arising on the left side)
2. Dilated main pulmonary artery
3. Aneurysm of arch or upper descending thoracic aorta
4. Vertical vein in total anomalous or hemi-anomalous pulmonary venous connection
5. Aneursym of the ductus arteriosus
6. Partial absence of left pericardium causing bulge of cardiac structures to the left
7. Left atrial appendage and submitral aneurysm (a little lower on the silhouette)