Differential diagnosis of a lateral cervical cyst and solitary cystic lymph node metastasis of occult thyroid papillary carcinoma.

We present a case of solitary cystic lymph node metastasis from an occult thyroid papillary carcinoma mimicking a lateral cervical cyst, and a case of thyroid papillary carcinoma with a true lateral cervical cyst. Based on a comparison of the radiographical findings of the two cases, differential diagnosis between cystic lymph node metastasis of papillary carcinoma and branchial cyst is discussed.