title: Invasive fibrous thyroiditis (Riedel thyroiditis): the Mayo Clinic experience, 1976-2008.
abstract: BACKGROUND
  Invasive fibrous thyroiditis (IFT) is the rarest form of thyroiditis, and reports are often limited to case reports and small case series. In this study, we aimed to summarize our institutional experience with IFT since 1976.
  
  
  METHODS
  We retrospectively reviewed the cases of all patients with IFT evaluated at Mayo Clinic, Rochester, Minnesota, from 1976 through 2008, with special emphasis on clinical presentation, associated risk factors, associated comorbid conditions, complications, and treatment.
  
  
  RESULTS
  Twenty-one patients met our inclusion criteria of (i) IFT confirmed by pathologic review at our institution and (ii) evidence of extension of fibrosis outside the thyroid capsule. Most patients (17, 81%) were women (mean age, 42 years). Presenting symptoms included pain (24%), dysphagia (33%), vocal cord paralysis (29%), and tracheal narrowing (48%). Three patients had associated hypoparathyroidism. Sixteen (76%) had a history of tobacco use, and 10 (48%) were current smokers. Fibrosing mediastinitis was present in four, orbital fibrosis in one, retroperitoneal fibrosis in three, and pancreatic fibrosis in one (38% had extracervical fibrotic processes). Eighteen patients had partial thyroidectomy, 7 (39%) of whom had surgical complications involving vocal cords and parathyroid. Two required tracheostomy. Thirteen had corticosteroid therapy; six received tamoxifen. There was no cause-specific mortality, and the fibrotic process stabilized or partially resolved in all patients.
  
  
  CONCLUSIONS
  IFT often is associated with a systemic extracervical fibrotic process and tobacco use. Attempted thyroid resection often results in postoperative complications. Long-term follow-up showed no deaths from IFT and showed stability of the thyroiditis.
authors.affiliation: Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA. fatourechi.vahab@mayo.edu
authors.forename: Mitra M
authors.initials: MM
authors.lastname: Fatourechi
authors.forename: Ian D
authors.initials: ID
authors.lastname: Hay
authors.forename: Bryan
authors.initials: B
authors.lastname: McIver
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Sebo
authors.forename: Vahab
authors.initials: V
authors.lastname: Fatourechi
mesh_terms: D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D005260:Female; D005355:Fibrosis; D006801:Humans; D008297:Male; D008875:Middle Aged; D012907:Smoking / Q000009:adverse effects; D013629:Tamoxifen / Q000627:therapeutic use; D013961:Thyroid Gland / Q000276:immunology; D013965:Thyroidectomy / Q000009:adverse effects; D013967:Thyroiditis, Autoimmune / Q000175:diagnosis / Q000188:drug therapy / Q000473:pathology* / Q000601:surgery; D014826:Vocal Cord Paralysis / Q000209:etiology
chemical_list: D000305:Adrenal Cortex Hormones; D013629:Tamoxifen