Duplicated thyroglossal duct cyst with intrathyroidal involvement in a paediatric patient.

Introduction: Thyroglossal duct cysts are the most common congenital cervical lesions in childhood. Intrathyroidal location and duplication or bifurcation of the duct are exceptionally rare variants.

Case report: An 11-year-old boy presented with two cervical masses: one subcutaneous lesion in the left infrahyoid region and another deep lesion in the right thyroid lobe. Ultrasonography and magnetic resonance imaging identified a 2 × 2 cm intrathyroidal cyst and a 3 × 3 cm subcutaneous lesion, findings consistent with a duplicated thyroglossal duct cyst with intrathyroidal involvement. A Sistrunk procedure was performed, with en bloc excision of both lesions. Histopathological examination confirmed ductal duplication, with one branch extending into the thyroid gland.

Comments: This case highlights the importance of advanced imaging in atypical or recurrent cervical lesions and emphasises the need to consider uncommon embryological variants of the thyroglossal duct.