Riedel Thyroiditis Associated With Massive Neck Fibrosis

Abstract

Riedel thyroiditis, also known as invasive fibrous thyroiditis, is a rare disorder of unknown etiology in which fibrous tissue replaces the normal thyroid gland and extends into adjacent tissues. The differential diagnosis includes carcinoma, lymphoma, and Hashimoto thyroiditis, but the extent of the fibrosis in these disorders is much less, and these entities usually do not extend beyond the thyroid. Sonographic features resemble those of acute or chronic thyroiditis with adjacent soft tissue extension. Here we present the imaging features of Riedel thyroiditis associated with massive neck fibrosis.