Endocrine Abstracts

Introduction: The malignant degeneration of thyroglossal duct cyst (TDC) is a very rare phenomenon. It occurs 1% of operated cysts. The incidence appears to be greatest in patients in the fifth decade with a slight preponderance in women. Papillary carcinoma represents the most common histologic type. In this study, we report 3 cases of a papillary carcinoma of thyroid occurring in a TDC in adult population in order to present diagnosis and therapeutic aspects of degenerated thyroglossal duct cyst.

Patients and methods: This is a retrospective study of adult patients who underwent surgery for thyroglossal duct cyst at Fattouma Bourguiba University Hospital between 2006 and 2019, and for whom the pathological study revealed a TDC carcinoma.

Results: Of 61 cases of TDC, 3 (4.9%) were found to have TDC carcinoma. Our study investigated two women and one men. The mean age was 42.3 years. All three patients presented with a painless, slowly growing anterior neck mass of several months duration. They had no past history of irradiation. Physical examination was remarkable for a midline neck mass located above the thyroid gland. The mean diameter of the mass was 4 cm. It was non-mobile with swallowing in 2 cases. In all patients, the thyroid gland examination was normal, as were thyroid function tests. Cervical ultrasound and computed tomography scan were performed. Therefore, a diagnosis of TDC was made, and the patients underwent a Sistrunk operation; the cyst was found to be separate from the thyroid gland, which was itself normal. The frozen section from the mass was done in two cases and confirms the diagnosis of papillary carcinoma. A total thyroidectomy with central neck dissection were performed. The final histologic exam confirmed a thyroglossal duct papillary carcinoma in all patients. Wider resection is so indicated in the third case. A complementary treatment by radioactive iodine 131 and thyroxine suppressive treatment were undertaken. The follow-up was marked by the absence of recurrence in a patient and the death in another patient. The third case was not followed up.

Conclusions: Thyroglossal duct carcinoma, most commonly papillary carcinoma, is a rare condition that should be considered in patients presenting with cystic midline neck masses. Surgery and complete excision is the main treatment and the optimal patient management includes multidisciplinary consultation in order to improve survival. The diagnosis of malignancy is made postoperatively, as in the present cases.