Thyroglossal duct cyst carcinoma is rarely mentioned in literature representing only 0,7-1,6% of cases with these embryonic remnants. Two patients with thyroid duct cyst carcinoma, a 14-year-old girl and a 44-year-old man operated on in our department, both diagnosed postoperatively are described. In the first one a classical Sistrunk operation was performed removing a 3 cm asymptomatic mass, a milimetric papillary carcinoma being incidentally discovered at paraffin section pathology. The second case presented a 4 cm cyst with benign clinical and ultrasonic features excepting a 8 mm nodule in the right thyroid lobe. Cytology was inconclusive such as a Sistrunk procedure together with a right thyroid lobectomy were done. Pathology revealed a limited carcinomatous focus in the cyst wall but also a papillary thyroid microcarcinoma. Both cases was thereby diagnosed only after microscopic examination. Conservative approach adopted due to "œinnocent" clinical appearance, subcentimetric size and absence of any risk factor in the two cases achieved stable, verified over time healing confirming the favorable prognosis of this rare pathology.