# Feasibility of Intraoperative Transoral Ultrasonography during the Sistrunk Procedure for Thyroglossal Duct Cysts Located on the Dorsal Side of the Hyoid Bone: A Case Report

## TL;DR

This case report shows how intraoperative transoral ultrasonography helped safely remove a hard-to-reach thyroglossal duct cyst in a child.

## Contribution

Demonstrates the feasibility of using transoral ultrasonography during Sistrunk procedures for deep thyroglossal duct cysts.

## Key findings

- TOUS provided real-time visualization of a deep TGDC on the dorsal side of the hyoid bone.
- The cyst was successfully excised without rupture using TOUS guidance.
- No recurrence was observed at 4-month follow-up after the procedure.

## Abstract

Thyroglossal duct cysts (TGDCs) are the most common congenital midline neck masses encountered in pediatric populations and are usually located anterior to the hyoid bone, making them readily identifiable by both superficial ultrasonography and skin palpation. However, intraoperative identification can be challenging in cases in which the cyst is located on the dorsal side of the hyoid bone or near the base of the tongue, which increases the risk of incomplete excision or rupture. This report describes the pediatric case of a TGDC located between the hyoid bone and the foramen cecum that was safely excised under intraoperative transoral ultrasonography (TOUS) guidance to facilitate identification of the entire cyst.

An 11-year-old boy was referred for evaluation of an incidentally detected midline neck mass. Neck ultrasonography and MRI revealed the presence of a 7-mm cyst located between the hyoid bone and the foramen cecum, consistent with the characteristics of a TGDC, and a Sistrunk procedure was scheduled. Intraoperatively, the cyst was successfully identified using TOUS with a small convex probe, which provided a stable and continuous view from the oral side throughout the dissection. A transverse cervical incision was made, the central hyoid bone was removed, and the cyst was visualized on its dorsal side under TOUS guidance. En bloc resection of the entire cyst and tract was completed without rupture, and histopathology confirmed the diagnosis of TGDC. The postoperative course was uneventful, and no recurrence was observed at the 4-month follow-up assessment.

The use of TOUS enabled real-time visualization of a deep TGDC structure that was difficult to identify via superficial ultrasonography after neck incision. Thus, TOUS can serve as a reliable guide during the Sistrunk procedure, reducing the risk of cyst rupture and incomplete resection, thereby enabling safe and complete excision. The experience of this case highlights the potential benefit of using TOUS in managing deep TGDCs located on the dorsal side of the hyoid bone, especially in pediatric patients.