[Riedel's thyroiditis: a report of a case with fatal outcome].

The Riedel's thyroiditis is a chronic inflammatory disease of the thyroid gland characterized by a process of fibrosis that destroys the gland partially, extending to the adjacent cervical structures. Its origin is unknown, although there are several theories in this respect. The clinical manifestations are not specific and it confuses frequently with neoplasia or infection, like a hard and painless thyroid mass that causes compressive symptoms. In this work, we report a case with lethal outcome.