A 5-year-old child presented with a submental swelling that had been progressively enlarging over approximately one year. The swelling was non-tender and had no associated symptoms such as fever or dysphagia. The child’s medical history included a tonsillectomy performed three years prior. There were no other significant medical, surgical, or family history findings.

Laboratory investigations were unremarkable, with normal thyroid function tests:

• Thyroid-Stimulating Hormone (TSH): 2.04 µIU/mL
• Free T4 (FT4): 16.6 pmol/L

• A midline ill-defined, inhomogeneous hypoechoic complex nodule (11 × 12 × 10 mm) located at the level of the hyoid bone and involving the subcutaneous tissue, consistent with a complicated thyroglossal duct cyst.
• Mild peripheral vascularity surrounding the lesion.
• Bilateral cervical lymphadenopathy, more prominent on the right side, with lymph nodes varying in size and shape. The largest measured 23 × 8 mm in the right submandibular region. All lymph nodes demonstrated benign characteristics, including cortical thickness <4 mm, preserved shape, and hilar echotexture, suggestive of inflammatory lymphadenopathy.
• Both thyroid lobes were normal in size, echotexture, and free of focal lesions.

The patient underwent a Sistrunk operation, which involved the complete resection of the thyroglossal duct to the base of the tongue, removal of the cyst, and excision of the central portion of the hyoid bone.

The histopathology report confirmed the diagnosis of a thyroglossal duct cyst with evidence of chronic inflammation. No malignancy or ectopic thyroid tissue was identified.

This case highlights the presentation and management of a complicated thyroglossal duct cyst in a pediatric patient. Thyroglossal duct cysts are the most common congenital midline neck masses in children, arising from the persistence of embryological remnants of the thyroglossal duct. Complications, such as secondary infection or the presence of inflammatory changes, can obscure the diagnosis and make surgical planning challenging.

Preoperative imaging, particularly neck ultrasound, is essential in identifying the cyst, ruling out ectopic thyroid tissue, and assessing lymphadenopathy. In this case, the inflammatory changes within the cyst and the reactive cervical lymphadenopathy likely resulted from chronic irritation or low-grade infection.

The Sistrunk operation remains the gold standard for treating thyroglossal duct cysts, as it significantly reduces the risk of recurrence compared to simple cyst excision. The patient’s histopathology findings confirmed inflammation without malignancy, underscoring the importance of histological evaluation to exclude rare complications such as carcinoma within the cyst.

This case illustrates the effective management of a complicated thyroglossal duct cyst in a child. Early diagnosis, comprehensive evaluation, and appropriate surgical intervention are critical to achieving excellent outcomes. Follow-up care is essential to monitor for recurrence and ensure complete resolution of the condition.