Papillary thyroid carcinoma metastasis to a branchial cleft cyst: a case report and review of imaging.

Branchial cleft cysts are the most common lesions in the lateral neck with ectopic thyroid tissue found only rarely within these cysts. Over the years, multiple cases of papillary thyroid carcinoma arising from these ectopic thyroid tissues have been described in the literature with these cases sharing a normal thyroid gland on surgical and histological evaluation. Recently, however, there are three cases of papillary thyroid carcinoma in a branchial cleft cyst reported to be the result of metastasis from a thyroid primary.