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CASE OF THE MONTH

PRESENTED BY

THE THYROID SURGERY CENTER OF TEXAS, P.A.

1927 Lohmans Crossing Road, Suite 201, Austin, TX 78734

www.thyroidcancer.com

512-608-9595; Fax-512-608-9833

Hashimoto’s Thyroiditis and Aortic Malformation

This patient is a 56 y/o lady, referred to us by a Texas endocrinologist. who underwent a CT scan of the chest for non thyroid related reasons and a 4.3cm mass was identified in the upper mediastinum behind the sternum. She had been diagnosed with hypothyroidism many years ago and was taking Synthroid 125mcg daily.

Her most recent TSH was 3.4 , her cholesterol was slightly elevated. Other past medical and surgical history was non-contributory, although she did learn just two days before her surgery that her brother suffered from Hashimoto’s thyroiditis. What was very significant, however, was the finding of a right sided aorta on the CT scan. An ultrasound was then performed and described a 4.7cm mass extending inferiorly from the level of the clavicle into the superior mediastinum. This mass was very dense and filled with microcalcifcations. An additional mass 2.2cm in diameter was described in the right lobe. No needle biopsy was performed.

On examination the thyroid gland really wasn’t very palpable at all and the upper pole of this left sided retrosternal mass could just barely be felt. This was suprising given all the ultrasound findings. The patient elected to undergo surgery and an uneventful total thyroidectomy with resection of substernal tumor was performed as an outpatient/overnight observation patient. The final diagnosis was extensive lymphocytic thyroiditis with dense sclerosis and calcification.

So far this is all pretty routine stuff, but what I haven’t yet mentioned are the possible implications of a right sided aorta in thyroid surgery. Ordinarily the arch of the aorta goes up and over the left main stem bronchus. On the left side of the neck, the vagus nerve descends form the base of the skull all the way down to the abdomen, but a small branch comes off at the level of the ductus arteriosus (which connects the aorta with the pulmonary artery), goes around it and then ascends into the neck once again, ultimately going into the voice box to innervate the left vocal cord, thus the naming of this nerve branch as the left “recurrent” laryngeal nerve because it was in the neck once, went down into the chest, and then returned. On the right side, a branch comes off the vagus nerve to go around the subclavian artery and ascend in the neck and up into the larynx to innervate the right vocal cord. This is the right recurrent laryngeal nerve. But all of this is under normal circumstances. When a congenital malformations such as a right sided aorta occurs, there are a number of possible variations in the anatomy of the recurrent laryngeal nerves on both sides. These include, but are not limited to, a non recurrent left laryngeal nerve (exceedingly rare), a non recurrent right laryngeal nerve, a right recurrent laryngeal nerve that actualls goes around the right sided aorta, or a left recurrent nerve that goes around the ductus arteriosus in the opposite direction than normal. From looking at the literature, it would appear that the number of possible variations in the anatomy of the recurrent laryngeal nerve in patients with a right sided aorta is quite enormous.

So what about our patient here, you say? Well, she had recurrent nerves that, while a little out of normal position, basically followed their normal anatomical paths and her postoperative voice is strong and normal.

Photo #1: This is the CT scan showing this large substernal tumor displacing and compressing the trachea. The right sided aorta is identified giving off an innominate artery on the left that then in turn gives off the left common carotid artery. Note how the tumor is wedged in among these great vessels and the trachea.

Photo #2 : This is the large tumor delivered up ionto the neck incision from below the sternum after disecting it free from the carotid arteery, the trachea, and the innominate artery.

Photo #3 :The remainder of the total thyroidectomy specimen

Photo #4 : This is a different patient showing a right non-recurrent laryngeal nerve. Note how it doesn't come up from the chest , but rather comes
off the vagus nerve at a right angle to cross the carotid artery and soft tissue before entering the larynx.

Photo #5 : This photo demonstrates the typical, usual, most common
location of the right recurrent nerve.

“…Thyroid surgery…it’s all we do…”