[Squamous cell carcinoma in a thyroglossal duct cyst].

OBJECTIVE To present a case of squamous cell carcinoma developed on a thyroglossal duct cyst in an adult patient. Modalities of treatment and prevention are discussed. PATIENT AND METHODS A 55-year-old woman had a thyroglossal duct cyst since childhood. Surgical resection had not been performed because of parental refusal. RESULTS Diagnosis of malignant degeneration was suggested by an increase in volume associated with cervical pain. Surgery was incomplete because of carotid artery and laryngeal involvement. Postoperative radiotherapy was given. At two years follow-up, local progression was controlled by palliative chemotherapy. DISCUSSION For most authors, the risk of recurrent infections is the main reason for surgical resection of a thyroglossal duct cyst during childhood. The risk of malignant degeneration is generally not put forward. It is rather uncommon for carcinoma to develop on a thyroglossal duct cyst. The risk is probably underestimated because surgery is generally performed early in childhood. CONCLUSION This observation of malignant degeneration emphasizes the importance of surgical resection of thyroglossal duct cysts during childhood. We discuss treatment in the event of malignant degeneration.