title: Clinical features of a new disease concept, IgG4-related thyroiditis.
abstract: OBJECTIVE
  Immunoglobulin (Ig)G4-related disease is a recently proposed systemic disorder that includes autoimmune pancreatitis (AIP), Mikulicz's disease, and various other organ lesions. In the present retrospective study, we examined whether thyroid lesions should also be included in IgG4-related disease (Ig4-RD) under the new term IgG4-related thyroiditis.
  
  
  METHODS
  We enrolled 114 patients with Ig4-RD, including 92 patients with AIP, 15 patients with Mikulicz's disease, and seven patients with IgG4-related cholangitis, and analysed clinical findings, function, serum values of activity markers, computed tomography (CT) images, and histology of the thyroid gland.
  
  
  RESULTS
  Among the 22 patients (19%) in our cohort who were found to have hypothyroidism [thyroid stimulating hormone (TSH) > 4 mIU/L], 11 patients had clinical hypothyroidism [free thyroxine (FT4) < 1 ng/dL] and 11 patients had subclinical hypothyroidism (FT4 ≥ 1 ng/dL). Serum concentrations of IgG, IgG4, circulating immune complex (CIC), and β2-microglobulin (β2-MG) were significantly higher in the hypothyroidism group compared with the remaining 92 euthyroid patients, and serum C3 concentration was significantly lower. After prednisolone treatment, TSH values had decreased significantly (p = 0.005) in this group and FT4 values had increased significantly (p = 0.047). CT images showed that the thyroid glands of patients with clinical hypothyroidism had a significantly greater volume than those of the euthyroid and other groups. Pathological analysis of one resected thyroid gland disclosed a focused lesion with infiltration of lymphocytes and IgG4-bearing plasma cells and loss of thyroid follicles.
  
  
  CONCLUSIONS
  Thyroid lesions associated with hypothyroidism can be considered as a new disease termed IgG4-related thyroiditis. Awareness of this condition should lead to appropriate corticosteroid treatment that may prevent progression to a fibrous state.
authors.affiliation: Department of Gastroenterology, Shinshu University School of Medicine, Matsumoto, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Watanabe
authors.forename: M
authors.initials: M
authors.lastname: Maruyama
authors.forename: T
authors.initials: T
authors.lastname: Ito
authors.forename: Y
authors.initials: Y
authors.lastname: Fujinaga
authors.forename: Y
authors.initials: Y
authors.lastname: Ozaki
authors.forename: M
authors.initials: M
authors.lastname: Maruyama
authors.forename: R
authors.initials: R
authors.lastname: Kodama
authors.forename: T
authors.initials: T
authors.lastname: Muraki
authors.forename: H
authors.initials: H
authors.lastname: Hamano
authors.forename: N
authors.initials: N
authors.lastname: Arakura
authors.forename: M
authors.initials: M
authors.lastname: Kadoya
authors.forename: S
authors.initials: S
authors.lastname: Suzuki
authors.forename: M
authors.initials: M
authors.lastname: Komatsu
authors.forename: H
authors.initials: H
authors.lastname: Shimojo
authors.forename: K
authors.initials: K
authors.lastname: Notohara
authors.forename: M
authors.initials: M
authors.lastname: Uchida
authors.forename: S
authors.initials: S
authors.lastname: Kawa
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001327:Autoimmune Diseases / Q000150:complications / Q000175:diagnosis*; D002761:Cholangitis / Q000150:complications / Q000175:diagnosis / Q000276:immunology; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000150:complications / Q000175:diagnosis* / Q000276:immunology*; D007074:Immunoglobulin G / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D008882:Mikulicz' Disease / Q000150:complications / Q000175:diagnosis* / Q000276:immunology; D010195:Pancreatitis / Q000150:complications / Q000175:diagnosis* / Q000276:immunology; D011379:Prognosis; D012189:Retrospective Studies; D018570:Risk Assessment; D012737:Sex Factors; D018709:Statistics, Nonparametric; D013960:Thyroid Function Tests; D013967:Thyroiditis, Autoimmune / Q000150:complications / Q000175:diagnosis* / Q000276:immunology
chemical_list: D007074:Immunoglobulin G