Thyroglossal duct cyst carcinoma: Case report

Introduction: Considered the most common congenital anomaly in the development of the thyroid gland, the thyroglossal duct cyst (TDC) has an estimated prevalence of 7% of the population. Although the vast majority of these cysts are benign, around 1% of cases can become malignant. Aim: To report the history, evolution and management of a patient with a thyroglossal duct cyst that developed into a carcinoma, to review the pathophysiology of the disease and the scarce literature on the subject. Case summary: 40-year-old woman diagnosed in 2018 with TDC. She went to a head and neck surgeon in 2020 for a reassessment of the case, to whom she reported an increase in the nodule and local discomfort. Surgery was indicated to remove it. The anatomopathological examination carried out after the surgery revealed a suspicion of malignant transformation. An immunohistochemical test was carried out, which confirmed the suspicion. The patient was asked to return in 6 months and to undergo ultrasound to monitor the pathology. Discussion: The thyroglossal duct results in the thyroid descending from the base of the tongue to its final resting place in the anterior region of the neck in the midline. This tract should obliterate at the beginning of fetal life; failure in this involution can subsequently give rise to a cyst in this duct. The cyst is often noticed after an upper respiratory tract infection and, in rare cases, a carcinoma can develop from the walls of the cyst. Conclusion: CDT carcinoma cases should be discussed due to the scarcity of reports in the literature and their rare incidence in the clinical field.