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Thyroglossal Duct Cyst Cancer Diagnosis Is a Heterogeneous Group

by Amy E. Hamaker •

What are the best practices for thyroglossal duct cyst (TGDC) carcinoma management, especially that of the orthotopic thyroid gland?

Background: Although TGDC is common, primary carcinoma of the thyroglossal duct cyst (TGDC cancer) is rare, and is most typically papillary thyroid cancer (PTC). Currently, there is no consensus on optimal TGDC cancer management. Controversy mostly centers on the role of thyroidectomy, as well as lymph node dissection, postoperative thyroid suppression, and radioiodine treatment. It is often difficult to distinguish true TGDC cancer from other similar but discrete diagnoses, including pyramidal lobe PTC and Delphian node (i.e. prelaryngeal lymph node) PTC metastasis.

Study design: Retrospective review of 28 TGDC carcinoma (hospital-recorded diagnosis) patients.

Setting: Massachusetts Eye and Ear Infirmary and the Massachusetts General Hospital, Boston.

Synopsis: In patients undergoing surgical treatment for the first time, the Sistrunk procedure was performed in 70%, simple cyst excision in 12%, and total thyroidectomy with nodal dissection in 18%. Among revision surgery patients, total thyroidectomy with nodal dissection was performed in three; Sistrunk procedure with nodal dissection and Sistrunk procedure only were performed in one each. Histology was reported as classical PTC in 50% of cases, classical cystic in 46.4%, and follicular variant of PTC in 3.6%. When thyroid surgery was performed, 42% had a normal thyroid gland, 37% contained PTC, 16% had Hashimoto’s thyroiditis, and 5% had benign adenoma. Initial clinical diagnosis versus final pathological review diagnosis resulted in the following diagnostic assessment: TGDC carcinoma (53% of patients versus 14%), pyramidal lobe primary (11% versus 29%) metastatic midline Delphian lymph (4% versus 25%) and indeterminate/no definitive clinical diagnosis (32% in both). At follow-up, 11 patients had subsequent total thyroidectomy. When all thyroid surgeries (initial and subsequent) were grouped together, a total of 17 thyroidectomies were performed, with six cases positive for PTC overall. No patient had local, regional, or distant recurrence.

Bottom line: TGDC cancer diagnosis comprises a heterogeneous group that includes true TGDC cancer, pyramidal lobe primary, Delphian node metastasis, and indeterminate cases. The authors propose a new terminology of upper neck papillary thyroid carcinoma (UPTC) to denote this heterogeneous group and recommend a rational algorithm for management.

Citation: Zizic M, Faquin W, Stephen AE, et al. Upper neck papillary thyroid cancer (UPTC): a new proposed term for the composite of thyroglossal duct cyst-associated papillary thyroid cancer, pyramidal lobe papillary thyroid cancer, and Delphian node papillary thyroid cancer metastasis. Laryngoscope. 2016;126:1709-1714.