An unexpected finding: A case of papillary thyroid carcinoma within a lateral thyroglossal duct cyst

Thyroglossal duct cysts (TGDCs) are the most common congenital cysts in the anterior neck. The incidence of papillary thyroid carcinoma (PTC) being present within a cyst is less than 1% and in most cases, the diagnosis is made postoperatively. We present a 60-year-old female with PTC arising from a lateral TGDC, identified in pathologic study after intra-oral excision of the cyst. Further thyroid ultrasound and fine-needle aspiration of a highly suspicious lesion at the superior pole of the left thyroid lobe showed PTC. The patient then underwent left hemithyroidectomy, isthmusectomy, ipsilateral and central neck dissection revealing PTC with ipsilateral nodal metastasis. The patient later underwent completion thyroidectomy and right neck dissection which did not reveal any additional malignant disease or nodal metastasis.