Occult Papillary Thyroid Carcinoma Presenting as Huge Cervical Metastasis with Cystic Pattern

Cervical cysts are usually benign in the population younger than 40 years. However, neck metastasis from malignancies of the head and neck may present as cervical cysts. Here, we report a case of papillary thyroid carcinoma with cervical metastasis and cystic change. A 35-year-old man visited our clinic, and his chief complaint was related to the presence of a huge neck mass for 15 years. Computed tomography scans revealed cystic masses and abnormal calcification in the thyroid gland. Fine needle aspiration cytology of the left thyroid gland revealed atypical cells with a few cells harboring intranuclear pseudoinclusion. We then performed dissection of the left side of the neck to remove the cystic masses and a left thyroid lobectomy. Intraoperative frozen section biopsy of the cystic masses showed benign cystic lesions. However, the results of the final pathologic examination proved thyroid papillary carcinoma in the thyroid gland and the cystic masses. The patient received dissection of the right side of the neck accompanied by right thyroid lobectomy. After the operation, 131I ablation therapy was performed. There was no recurrence noted during the regular 2-year follow-up period.