Riedel's thyroiditis.

Invasive fibrous (Riedel's) thyroiditis is a rare thyroid condition of unknown origin that may be associated with inflammatory fibrosclerosing processes elsewhere in the body. Although the condition is benign and self-limiting, its importance lies in its ability to clinically mimic carcinoma almost completely, necessitating performing an open biopsy to establish the correct diagnosis. In a review of over 700 thyroid operations performed at Loma Linda (Calif) University Medical Center in the past 15 years, we encountered only one documented case of Riedel's thyroiditis. Our patient presented with a firm thyroid mass, vocal cord paralysis, and symptoms of esophageal compression. Surgery was performed to obtain a definitive diagnosis and prevent the possibility of subsequent additional tracheal compression with airway compromise. The pathologic findings, as well as the medical and surgical treatment of this condition, are reviewed.