Muppet wants to leave air-fluid levels behind and put your collective minds to work!
The first case of 2013 presents the radiographs of a 56-year-old female who came to the emergency room with syncope. There is an abnormal opacity in the aortic knob. What do you think it is?
1. Vein
2. Aneurysm
3. Lymph node
4. Tumour
Findings: PA chest shows a rounded opacity over the aortic knob (arrow), with a faint line above it (
red arrow). There is a double contour of the left mediastinal line (
yellow arrows). SVC and azygos vein are not visible.
The rounded shadow at the aortic knob is a typical aortic nipple, secondary to an enlarged left superior intercostal vein (LSIV) which joins superiorly (
red arrow) the brachiocephalic vein and inferiorly the hemiazygos vein (
yellow arrow). Absent SVC is associated to syncope, secondary to arrhythmias. In this patient, a good possibility is absent SVC with drainage of the blood trough the hemiazygos system.
Axial CT confirms the absent SVC (neither right nor left) and the enlarged LSIV. CT reconstructions show the hemiazygos vein (arrows) parallel to aorta (A), draining blood from the brachiocephalic veins.
Teaching point: a small aortic nipple is a normal finding. When enlarged, suggests obstruction of SVC/IVC, with drainage through the azygos/hemiazygos system.
