There have been few reports of mature cystic teratoma, also known as a dermoid cyst, in the head and neck. Cervical neck teratoma extending into the mediastinum is also relatively rare. Here, we report a mature teratoma found in a cervical tumor in a 21-year-old man. This is the first reported case of a mature cervical teratoma extending into the anterior mediastinum. A combination of frontal X-ray, ultrasonography, computed tomography, and magnetic resonance imaging indicated a large oval heterogeneous mass surrounding the thyroid gland and trachea, underneath the sternocleidomastoid and sternohyoid, which pressed on the left lobar thyroid and trachea and extended into the anterior mediastinum. Based on preoperative observation, a diagnosis of an embryonal benign tumor was made. Although rare, this case demonstrates that these tumors should be completely removed during workup of cervical tumors.
Keywords: anterior mediastinal; cervical; surgery; teratoma.