Mature Cystic Teratoma of the Thyroid in an 11-Year-Old Child: A Case Report

Mature thyroid teratomas are rare, particularly beyond the neonatal period, and may resemble more common congenital anterior neck lesions.An 11-year-old boy presented with a five-year history of a slowly enlarging anterior neck mass associated with exertional dyspnea.The mass moved with swallowing.Ultrasonography demonstrated a large cystic midline and paramedian lesion with internal echoes and a category 4 nodule in the right thyroid lobe according to the American College of Radiology Thyroid Imaging, Reporting, and Data System (TI-RADS).Fine-needle aspiration cytology of the nodule showed benign lymphoid tissue, and aspiration of the mass showed anucleate squames only, without follicular cells.Magnetic resonance imaging and computed tomography revealed a 42 x 65 x 63 mm heterogeneous lesion containing cystic, fatty, soft-tissue, and calcific components, inseparable from the inferior right thyroid lobe and displacing the trachea to the left without local invasion.The patient underwent right thyroid lobectomy.Histopathological examination identified mature derivatives of all three germ layers without immature elements, atypia, or malignancy, confirming a mature cystic teratoma.Recovery was uncomplicated.At three months, the patient was asymptomatic with an intact voice, showed no clinical evidence of recurrence, and postoperative thyroid function was normal.This case emphasizes the value of correlating imaging, cytology, operative findings, and histopathology when a pediatric neck mass has overlapping thyroglossal duct cyst, dermoid cyst, and teratomatous features.