Management of well-differentiated thyroid carcinoma presenting within a thyroglossal duct cyst

Background and objective: Well-differentiated thyroid carcinoma (WDTC) is diagnosed in approximately 1.5% of thyroglossal duct cysts (TGDC). No clear consensus exists regarding further management after adequate excision of the cyst, especially the role of total thyroidectomy and postoperative radioactive iodine therapy. The current review was undertaken in an attempt to clarify these issues.

Methods: Demographic, clinical, tumor, treatment, pathology, and outcome data on 57 eligible patients reported in recent literature were pooled together with 5 patients treated at our institution for this analysis.

Results: A Sistrunk operation was performed for resection of the thyroglossal duct cyst in the majority (90%) of patients. Histologic examination of the tumor in the cyst revealed that papillary carcinoma was the most frequent (92%) histologic type. A total thyroidectomy was performed consequent to the diagnosis of thyroglossal duct cyst carcinoma in approximately half of the 62 patients. A malignant tumor was reported in 27% of the thyroidectomy specimens. Postoperative radioactive iodine therapy was administered in 16 (26%) patients. With a median follow-up of 71 months (range 1-456 months), the 5- and 10-year Kaplan-Meier overall survival was 100 and 95.6%, respectively. There were no disease-related deaths reported in any of the patients. Univariate analysis revealed that the only significant predictor of overall survival was the extent of primary surgery for the thyroglossal cyst. The addition of total thyroidectomy to Sistrunk operation did not have a significant impact on outcome (P = 0.1). Patients treated with postoperative radioactive iodine (RAI) fared significantly worse than those that did not need RAI, which may be explained by the fact that this modality would generally be used in patients with higher risk tumors.

Conclusions: The Sistrunk operation is adequate for most patients with incidentally diagnosed TGDC carcinoma in the presence of a clinically and radiologically normal thyroid gland. Results of adequate excision using the Sistrunk operation are excellent and the concept of risk-groups should be used to identify patients, who would benefit from more aggressive treatment.