Today´s radiographs belong to a 48-year-old woman with aortic stenosis.
Most likely diagnosis:
1. Intrathoracic goiter
2. Aortic arch malformation
3. Neurogenic tumor
4. Any of the above
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Findings: PA radiograph shows a left mediastinal mass superimposed on the artic knob (A, arrow). The trachea is not displaced. In the lateral view the mass is in the anterior/middle mediastinum (B, arrows).
Regarding the diagnosis offered, the location excludes neurogenic tumor which usually arises in the posterior mediastinum. Intrathoracic goiter is a possibility, but the fact that part of it is the anterior mediastinum and that there is no tracheal displacement goes against this diagnosis. The location of the mass around the aortic knob plus knowing that the patient has aortic valve stenosis point to an aortic arch malformation.
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Enhanced CT shows that the mass corresponds to a high aortic knob (C, arrow). An oblique view demonstrates the high knob (D, arrow) with a kink and angulation of the aorta representing the lower knob in the PA radiograph (D, red arrow).
My apologies for showing only 3-D images, but the CT was done during the lockdown and they are all I could get.
The patient has no collateral circulation. He had no systemic hypertension and no gradient across the zone of kinking.
Final diagnosis: aortic pseudocoarctation
Pseudocoarctation of the aorta occurs when the aortic arch originates from the 3rd arch, instead of the 4th. In this condition, the aortic arch is higher than usual, with a kinking at the union of the aortic arch and descending aorta, simulating aortic coarctation. Rib notching is absent and systemic hypertension is not present.
This is a rare condition is, but it is not unusual to see it in clinical practice.
To compensate for the lack of CT images in this case, I am showing another pseudocoarctation with similar findings (Fig 1).
Fig 1. PA chest radiograph shows a superior middle mediastinal mass (A, arrow), displacing the trachea. Mass is vaguely seen on the lateral view (B, circle). The most common diagnosis should be an endothoracic goiter but remember that a vascular structure should be always ruled out with enhanced CT.
Coronal CT demonstrates that the mass corresponds to a dilated aortic arch located higher than usual (C, arrow). On the oblique reconstruction, the high aneurysmatic aortic arch is well seen as well as the kinking at the junction with the descending aorta (D, red arrow).
Final diagnosis: aortic pseudocoarctation with aneurysm of the aortic arch.