Riedel's thyroiditis in multifocal fibrosclerosis: CT and MR imaging findings

Riedel's thyroiditis is a rare disorder of unknown etiology and may be seen isolated or as a part of multifocal fibrosclerosis, It is important to dis tinguish Riedel's thyroiditis from thyroid carcinoma. Reports about imaging features of Riedel's thyroiditis are limited in the radiologic literature. We describe herein CT and MR imaging features of Riedel's thyroiditis in a case of multifocal fibrosclerosis with previously unreported radiologic ob servations.