The clinical features of thyroglossal duct remnant cysts (TGDC) have been well described, however the histopathologic aspects of these lesions have not been addressed in a detailed manner. In particular, there has been no large community practice based series evaluating TGDC histologically compared with management outcomes. A retrospective review of all TGDC diagnosed between 2005 and 2015 was performed. Six hundred eighty-five patients were identified (344 males; 341 females). Age at presentation was bimodal (first and fifth decades) and ranged from 0.8 to 87 years (mean 31.3 years). Males predominate in children (150:111); females in adults (230:194). Patients presented most frequently with a mobile midline neck mass in an infrahyoid location. An associated skin fistula (n = 67) was twice as common in pediatric as adult patients. The average cyst size was 2.4 cm (range 0.4-9.9 cm) by imaging studies and 2.6 cm (range 0.2-8.5 cm) by pathologic examination; pediatric patients had smaller cysts (mean 2.1 cm) than adults (mean 2.8 cm). Histologically, 257 (38 %) TGDC were lined by respiratory epithelium alone, 68 (10 %) squamous epithelium alone, 347 (51 %) exhibited both respiratory and squamous epithelium, and 13 (1 %) had no identifiable epithelial lining. Four hundred eighty-four (71 %) TGDC had associated thyroid gland tissue present within the cyst wall (n = 282), skeletal muscle (n = 71), adipose tissue (n = 34), or a combination of these sites (n = 97). The hyoid bone was identified in 647 (grossly and/or histologically), and absent in 38. Surgical management consisted of Sistrunk procedure (n = 647), cystectomy (n = 31), or thyroidectomy/thyroid lobectomy (n = 7). Treatment related complications were observed in 6 patients, which included vocal cord damage, seroma, and hematoma. Recurrences developed in 20 (3 %) patients, 14 of whom were managed initially by cystectomy. Papillary thyroid carcinoma was identified in 22 (3.2 %) TGDC. In summary, TGDC show a bimodal peak in the 1st and 5th decades, commonly presenting as a midline cervical lesion below the hyoid bone, associated with a skin fistula in 10 %. Histologically TGDC are most commonly lined by a combination of respiratory and squamous epithelium. Thyroid gland tissue is identified in 71 % of cases (0.45 cm mean size), although not limited to the cyst wall, but present in the surrounding soft tissues. Rare TGDC may harbor malignancy (3.2 %). TGDC are most effectively managed by Sistrunk procedure rather than excision, which carries low rates of complications (1 %) and recurrence (3 %).

Carcinomas arising from thyroglossal duct remnant cysts (TGDCs) are rare, without well-defined management and staging criteria. All TGDCs (n = 685) diagnosed between 2005 and 2015 were retrospectively reviewed, with 22 carcinomas identified (3.2 % incidence). Twenty-two patients (17 females, 5 males), aged 12-64 years (mean 39.9 years; median 39 years) were identified. An anterior, superior midline neck mass was the presenting symptom in all patients. A cancer diagnosis [all papillary thyroid carcinoma (PTC)] was made after the Sistrunk procedure (SP), with a Bethesda Category V or VI classification preoperatively by fine needle aspiration in 5 of 12 cases tested. A SP was performed in all patients, with total thyroidectomy concurrently (n = 4) or subsequently (n = 12). A selected neck dissection was performed in 5 patients, with metastases found in 3. Of the patients who had a thyroidectomy, syn-

Thyroglossal duct cyst (TGDC) carcinomas are rarely encountered in the pediatric population. The clinical behavior of these tumors in the pediatric setting is unclear and management is not well defined. Two cases of pediatric thyroglossal duct cyst carcinoma were identified in a review of all thyroglossal duct cysts diagnosed over a ten year period. These two cases were analyzed along with 57 cases of thyroglossal duct cyst carcinoma affecting patients less than 21 years of age compiled from the English literature. Fifty-nine patients (36 females, 23 males) aged 6-20 years (mean 15.0 years) were identified. All presented with an anterior midline neck mass, which was typically mobile and non-tender. The average tumor size was 2.6 cm. Histologically, all tumors were papillary thyroid carcinomas arising in a background of a thyroglossal duct cyst. The tumors exhibited a papillary, follicular, or mixed architecture with classical papillary thyroid carcinoma nuclear features. Soft tissue extension was present in 16 cases. All patients were managed surgically with a Sistrunk procedure, with additional thyroidectomy performed in 29 patients, combined with a lymph node dissection (n = 15), or a Sistrunk and lymph node dissection (n = 5). All patients were stage I at presentation, with 11 showing lymph node metastases. Postoperative radioactive iodine was employed in 20 patients. A papillary carcinoma of the thyroid gland was reported in four of the patients who had concurrent/subsequent thyroidectomies. Recurrences were reported in four patients, with distant metastases in one patient, who died of disease (13 months). Follow up data was available for 45 patients, with an overall mean follow-up of 54.5 months. All patients were alive, with the exception of one who died with disease. TGDC carcinomas in pediatric patients is associated with a good overall prognosis, best managed by Sistrunk procedure alone, with selected lymph node dissection if clinically indicated.