Lateral cervical cystic mass in a young adult very rarely could be a first sign of an occult thyroid papillary microcarcinoma metastasis. In this paper, we presented a 37-year-old male patient whose preoperative 6 cm left lateral cervical cystic mass was initially diagnosed as branchial cleft cyst, but then the postoperative histopathological examination of the mass was revealed as papillary th...