AA. present two cases of carcinoma arising on thyroglossal duct's cystic. Those carcinomas are a rare event and will be suspected in the patients that present an irregular tumefaction of medial neck's district. Etiology is unknown; is possible that a preceding irradiation on the neck will represent a factor risk. AA. retained that in case of medial neck's district tumefactions is necessary executed a total examination of neck's and head's district, an echography, a thyroid scintigraphy, a thoracic radiography, a panendoscopy and a FNAB. When we found a squamous carcinoma on residual thyroglossal duct the therapy is chirurgical in function of dimension of T and N with following radiotherapy in function of stage (possible lymph node metastasis). When we found a different adenoma is necessary chirurgical removal of tumefactions with hyoid bone's a body resection (Sistrunk's operation) with total thyroidectomy and following Pochin's test for seeking eventual residual with radiometabolic and suppressive therapy.