In case of lateral cervical cystic lesions, the differential diagnoses include branchial cleft cyst(BCC), teratoma, dermoid, hemangioma and lymphangioma etc. But sometimes metastatic cystic lymph nodes may exist in lateral neck. In such circumstance, the primary lesions are known to stem from oropharynx, nasopharynx, salivary and thyroid gland etc. A-66-year-old-male came to our clinic, due to the lateral cervical mass for 5 years. We performed the neck CT, sonography and sono-guided FNAC. He was initially diagnosed with the benign cyst such as BCC. We performed the excisional biopsy on left level II, but the pathologic report was revealed as metastatic papillary thyroid carcinoma(PTC). And then he received the total thyroidectomy with neck dissection. The final diagnosis was cystic metastasis from PTC. We learn a valuable lesson form this case in the following. Even if the simple cervical cyst is presumed with radiology and clinical pattern, more careful considerations on the basis of history and radiologic findings are mandatory.