Introduction Thyroid tissue replaced by fibrous tissue can result in hypothyroidism histologically characterized by a dense fibroinflammatory infiltrate etiology unknown thought to be a manifestation of a systemic, fibroinflammatory disease Presentation Physical exam presents with fixed, hard goiter painless on palpation Treatment Medical corticosteroids tamoxifen Prognosis, Prevention, and Comlications Fibrosis may extend to locally to the trachea, parathyroid glands, and mediastinum may result in obstruction, dyspnea, hoarseness and hypoparathyroidism