Is this a second branchial cleft cyst?

One of the endocrinologists I work with, John Palmer DO, recently saw a patient with a left-sided thyroid cyst. She had had a thyroid ultrasound at an outlying hospital and then another one done through our local radiology department. Her thyroid-stimulating hormone level was normal. Nevertheless, before she came to see us she also had an I¹²³ uptake and scan which was also normal. There were no hot or cold areas.

The patient was sent to endocrinology in consultation. The lesion was hypoechoic and took up much of the left thyroid lobe. The echotexture within the lesion was somewhat more heterogenous than we usually expect in a simple thyroid cyst (see attached photos). There was no flow within this lesion and only minimal posterior enhancement. An ultrasound-guided fine- needle aspiration was attempted but was non-diagnostic.

Dr. Palmer wondered whether this might be a second brachial cleft cyst and asked my thoughts. I agree that more than likely this is what it is.

Second branchial cleft cysts are often found incidentally on imaging studies. They are usually found in the submandibular space but the location can be variable. Only about half are appreciated on physical examination. Most are asymptomatic but some patients may experience neck fullness or discomfort. A painful branchial cleft cyst suggests possible infection.

Second branchial cleft cysts classically appear to be an anechoic, well-circumscribed cyst by ultrasound. Most have no detectable wall and are unilocular. They can be anechoic, homogenously hypoechoic with internal free-floating debris or less often, hyperechoic with a pseudosolid appearance. Some have posterior enhancement while others do not.

I have performed and/or reviewed many hundreds of diagnostic thyroid ultrasounds. To my knowledge, this is the first probable second branchial cleft cyst we have found. However, it is possible there have been others that we did not recognize at the time.

I am curious if anyone else has experience identifying these. Do you think this a second branchial cleft cyst as we suspect it might be?

Am J Neuroradiol. 2000;21:315-319.