[Papillary carcinoma in an isthmic thyroglossal duct cyst: clinical considerations].

Cancer in a thyroglossal duct cyst is uncommon (incidence: approximately 1%). There are about 250 reported cases in the literature, most of which are papillary cancers or, less frequently, squamous or follicular carcinomas. The preoperative diagnosis of thyroglossal duct cyst carcinoma may be facilitated by an ultrasound neck examination or fine needle aspiration cytology (FNAc). As reported in the literature, however, the diagnosis is often obtained only at histopathological examination. We describe a case of a 43-year-old male patient with a papillary carcinoma in an isthmic thyroglossal duct cyst. Ultrasound of the neck demonstrated a nodular hypo-anechogenic cystic neoformation of the isthmus of the thyroid, while Fnac was not diagnostic. An isthmectomy of the thyroid was initially performed. Frozen examination of the cystic lesion revealed a papillary carcinoma in the thyroglossal duct cyst. A total thyroidectomy with central lymphectomy was therefore performed. Carcinoma in the thyroglossal duct has a low mortality (5-year mortality: < 2%), but a long-term follow-up is mandatory, due to the low, short-and medium-term recurrence rate.