A case report of papillary thyroid carcinoma arising from a thyroglossal duct cyst and brief literature review

Background Thyroglossal duct cysts (TGDC) are located in the midline of the neck, and are the most common developmental abnormality of the thyroid gland. Approximately 1% of TGDC are malignant, the most common malignant finding, papillary carcinoma of the thyroid gland. Due to the rarity of this entity, pathological staging criteria are not well established. Case report A 45-year-old woman presented with an anterior neck mass. Imaging showed a solid and cystic lesion anterior to the hyoid bone. US FNA was performed and was reported as consistent with papillary thyroid carcinoma. A subsequent total thyroidectomy and combined Sistrunk procedure was performed. Macroscopically, a solid and cystic mass was identified within the fibromuscular tissue associated with the TGDC, away from the thyroid gland. No suspicious areas were identified within the thyroid gland. Microscopically the solid and cystic mass demonstrated architectural and classical nuclear features of papillary thyroid carcinoma, including nuclear crowding, grooves and optical clearing. The tumour was completely excised, and no tumour foci were identified within the thyroid gland, which was examined in entirety, and none of the two adjacent lymph nodes were involved. Immunohistochemistry showed that the tumour was positive for CK19 and HBME-1.