Endocrine Abstracts

Thyroglossal duct cysts are the most frequently occurring congenital cervical anomaly, however the development of Papillary Thyroid Cancer (PTC) in these are very rare, with an incidence around 1%. We present two cases of PTC identified in thyroglossal duct cysts from our services. A 26-year-old lady with a 1-year history of midline neck swelling, was investigated with a neck ultrasound which showed a 2.8cm septated thyroglossal duct cyst and U2 thyroid cyst. She underwent a Fine needle aspiration which was S/O of PTC within the cyst. She went on to have surgery with removal of the thyroglossal cyst, total thyroidectomy and level 6 Lymph Node dissection. Histology showed 15mm papillary thyroid cancer within the fibrous tissue of thyroglossal duct. The thyroid gland showed nodular hyperplasia and no evidence of PTC. She was staged pT1b N0 (0/9). A 28-year-old lady was referred with a midline neck swelling. She was found to have a complex cystic mass S/O thyroglossal cyst and a thyroid nodule U2, which was managed with a sistrunk operation. Histology revealed the presence of 1.5cm PTC arising from within the thyroglossal duct cyst and was staged pT1bR1. She then underwent completion total thyroidectomy and level 6 lymph node dissection. The histology of which revealed a background lymphocytic thyroiditis, and 1/16 lymph nodes showed a small deposit of PTC. Final staging was pT1b N1a(1/16) R1. Patient received RAI 978MBq 131-I. Both the patients were started on levothyroxine, calcium and vitamin D supplements, and is having regular reviews in the outpatient setup. These cases highlight the importance of awareness of the rare occurrence of PTC within a thyroglossal duct cyst. There needs to be a high index of suspicion when dealing with such cases, as this commonly encountered benign lesion, does have the potential to harbour malignant tissue.