Thyroglossal Duct Cyst: Sonographic Findings Revisited

PURPOSE: The purpose of this study was to review and reevaluate the well-known ultrasonographic characteristics of cysts of the thyroglossal duct. MATERIALS AND METHODS: We retrospectively reviewed the ultrasonographic findings in 31 patients with pathologically proven cysts of the thyroglossal duct. Assessment involved the following variables: relationship to the hyoid bone, location, shape, size, margin, internal echogenicity, the presence of septa, solid component, and thickness of the cystic wall. The echogenicity of cystic contents was evaluated in 23 cysts for which surgical or aspiration biopsy reports were available. RESULTS: Cysts were closely attached to the hyoid bone in 30 cases (97%). Their location was infrahyoid in 14 cases, hyoid in 11, and suprahyoid in six; and midline in 18, both midline and off-midline in nine, and off-midline in four. A triangular shape was seen in 15 cases, a round or oval shape in 12, and a lobulated shape in three. Their diameter varied from 1 to 3.8 (mean, 2) cm, while internal echogenicity was hypoechoic in 12 cases, anechoic in ten, and isoechoic in nine. Septations were noted in six cases, and a solid component in two. The cystic wall was less than 1mm thick in 17 cases, even and greater than 1mm in eight, and uneven and greater than 1mm in six. Among 23 cases, the cystic contents were mucous in 18, serous in three, and purulent in two. The echogenicity of cysts with mucous content varied, while serous or purolent cysts were isoechoic. CONCLUSION: The characteristic sonographic finding of cyst of the thyroglossal duct is a centrally located triangular neck cyst, closely related to the hyoid bone.