Carcinoma insular de tiroides

: A new case of insular carcinoma of the thyroid gland is presented. It was described by Carcangiu et al(1) in 1984 as a poorly differentiated carcinoma, less of one hundred cases were published after its description. We report a case of a patient who was referred for compressive symptoms caused by a mediastinal mass. It was found a tumor of left thyroid lobe strongly adherent to adjacent structures, which was informed as a poorly differentiated insular carcinoma. She underwent total thyroidectomy and posterior treatment with an ablative dose of 1311. She is currently free of disease after one year of follow-up. The diagnosis, treatment, differential diagnosis with another thyroid carcinomas and the rarety of this type of tumors are analyzed. The importance of a correct diagnosis is fundamental in order to carry out an aggressive treatment and a more exhaustive follow-up in these patients, taken account its behavior and its poor prognosis when compared with well-differentiated carcinomas.