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Radiology
Case of the Month
| Case No. : | 10 |
| Month : | October |
| Year : | 1999 |
| Contributor : | Dr. Abhijit Raut |
| Clinical Presentation | Radiological Investigations | Radiological Findings | Diagnosis | Discussion |
A 36 year old man presented with left sided dull aching chest pain off and on since 2 months. He also complained of mild dysphagia. He was a known hypertensive on anti hypertensive drugs. Laboratory findings were within normal limits except for the ESR, which was raise to 40mm .
A frontal radiograph was of the chest was obtained as a part of routine investigation :
Fig. 1a
A Lateral radiograph of the chest :
Fig. 1b
A Esophagogram was performed :
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Fig. 2a
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Fig 2b
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Plain & contrast CT scan of chest was done :
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| Fig. 3a | Fig .3b |
Arch aortogram was then performed :
Fig .4
The frontal radiograph of the chest shows a right para tracheal soft tissue density mass behind the medial end of the right clavicle extending from the aortic knuckle .The medial margin of the lesion is silhouetting with the superior vena cava while the smooth lateral margin extends above the medial end of the clavicle. .
Lateral radiograph shows the opacity visualized in frontal view to be in the posterior mediastinum
The barium esophagogram shows an indentation on the a posterior wall of the supraaortic portion of esophagus.
Plain & contrast CT scans of the chest reveal the soft tissue density mass in the right para tracheal region seen on the frontal chest radiograph to be a partially thrombosed ecstatic (aneurysmal) vessel arising from the left side of the arch of aorta crossing the midline behind the esophagus and coursing to the right side. The descending thoracic aorta appears ectatic.
The arch aortogram shows mild dilatation of the ascending arch and visualized opacified lumen of the descending thoracic aorta .The right and left common carotid arteries show normal origins and are normal .The right subclavian artery shows an aberrant origin and mild fusiform dilatation in its initial 5 cms.The left subclavian artery shows a beaded appearance and mild dilatation .The left vertebral artery is normal.
Partially thromosed fusiform aneurysm of the proximal right aberrant subclavian artery affected by aortoarteritis..
An aberrant right subclavian artery can arise from a break in the hypothetical double aortic arch between the right common carotid and subclavian arteries resulting in formation of a left aortic arch with an aberrant right subclavian artery. It may also arise from an aortic diverticulum of Kommerell or directly from the aorta.
The aberrant right subclavian artery runs posterior to the esophagus. Since the vascular ring is not intact there is usually no associated dyspnea or dysphagia.
On plain frontal radiograph of the chest the right subclavian artery can be identified in the supra aortic area as a linear shadow extending upwards and to the right from the aortic knob .The vessel can also be seen through the tracheal air column and produces a mass effect behind the medial aspect of the right clavicle.
On the lateral chest radiograph the vessel causes a retrotracheal opacity ,obscures the aortic arch and produces an imprint on the posterior tracheal wall.
The aberrant right subclavian artery always passes behind the esophagus, causing an oblique notch on the posterior wall. It can be demonstrated on full column lateral barium swallow study.
The diagnosis of anomalous right subclavian artery can be made on computed tomography and is not infrequently encountered as an incidental finding .This is not surprising since anomalous right subclavian artery is not an uncommon developmental anomaly.
Findings at computed tomography are diagnostic :-