Carcinoma showing thymus-like elements (CASTLE) is a rare tumor arising in the thyroid gland. Fewer than 100 patients with this tumor, those predominantly from Eastern Asia, have been reported before. We present the first CASTLE case from Turkey. A 51-year-old male was admitted with a complaint of a neck mass and hoarseness. A laryngoscopic examination revealed left vocal cord paralysis. Neck ultrasonography showed a tumor which was compressing the esophagus and had invaded the left recurrent laryngeal nerve (RLN). The patient underwent a total thyroidectomy, a unilateral central-compartment neck dissection, and following adjuvant radiotherapy. Intraoperative nerve monitoring was performed during the operation to preserve the contralateral nerve. He completed a 3-year follow-up period after the completion radiotherapy, and no recurrence was observed. The treatment is controversial, although surgery with or without adjuvant radiotherapy appears to be the best choice. In cases of RLN destruction due to tumor invasion, we recommend using intraoperative nerve monitoring to preserve the contralateral RLN to avoid devastating complications, such as a tracheostomy.