Papillary carcinoma in a thyroglossal duct cyst: Two case reports and review of literature

Thyroglossal duct cysts are the most common form of congenital malformation in the neck. They develop from the epithelial remnants of the thyroglossal tract and 70% is diagnosed in childhood; 7% is diagnosed in adulthood. Carcinoma arising in these remnants constitutes a very uncommon histopathological entity. The diagnosis of malignancy is made incidentally on cytopathologic studies of the excised surgical specimen. Only 1% of thyroid carcinoma arises from the thyroglossal duct cysts and papillary carcinoma (80%) is the most common malignancy in this cyst. We describe here two cases of thyroglossal duct cysts. Surgical specimen histopathology study showed presence of papillary carcinoma in the first case. Thyroglossal duct cyst was preoperatively diagnosed via fine needle aspiration biopsy (FNAB) in the second case. We suggest that in adult cases of thyroglossal duct cysts, fine needle aspiration cytology should be used for preoperative diagnosis and frozen examination should be done intra operatively.