title: Immunohistochemistry of IgG4 can help subclassify Hashimoto's autoimmune thyroiditis.
abstract: IgG4-related sclerosing disease has been recently recognized as a systemic disease entity characterized by an elevated serum IgG4 level, sclerosing fibrosis and diffuse lymphoplasmacytic infiltration by many IgG4-positive plasma cells. Similar histopathological features have often been noted in the fibrous variant of Hashimoto's autoimmune thyroiditis, but thyroid gland involvement has been only briefly mentioned with regard to IgG4, and no immunohistochemistry for IgG4 has been reported in Hashimoto's autoimmune thyroiditis. Herein, the purpose of the present study was to investigate the infiltration of IgG- and IgG4-positive plasma cells on immunohistochemistry for a panel of thyroiditis samples (Hashimoto's autoimmune thyroiditis, n= 13; subacute thyroiditis, n= 2; lymphocytic thyroiditis, n= 2). Cases of Hashimoto's thyroiditis could be classified into two groups based on immunostaining of IgG4: IgG4 thyroiditis (IgG4-related, IgG4-positive plasma cell-rich thyroiditis) and non-IgG4 thyroiditis (non-IgG4-related, IgG4-positive plasma cell-poor thyroiditis). IgG4 thyroiditis presents with severe lymphoplasmacytic infiltration, dense fibrosis, marked follicular cell degeneration, oxyphilic change and lymphoid follicle formation, while non-IgG4 thyroiditis presents with relatively mild or absent histopathological characteristics. In conclusion, immunostaining of IgG4 can help subclassify Hashimoto's thyroiditis; and IgG4 thyroiditis may have a close relationship with IgG4-related sclerosing disease.
authors.affiliation: Department of Human Pathology, Wakayama Medical University, Wakayama 641-8509, Japan.
authors.forename: Yaqiong
authors.initials: Y
authors.lastname: Li
authors.forename: Yanhua
authors.initials: Y
authors.lastname: Bai
authors.forename: Zhiyan
authors.initials: Z
authors.lastname: Liu
authors.forename: Takashi
authors.initials: T
authors.lastname: Ozaki
authors.forename: Emiko
authors.initials: E
authors.lastname: Taniguchi
authors.forename: Ichiro
authors.initials: I
authors.lastname: Mori
authors.forename: Koji
authors.initials: K
authors.lastname: Nagayama
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Nakamura
authors.forename: Kennichi
authors.initials: K
authors.lastname: Kakudo
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000032:analysis; D005260:Female; D050031:Hashimoto Disease / Q000145:classification* / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis*; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D010950:Plasma Cells / Q000276:immunology*; D012598:Sclerosis / Q000473:pathology; D055815:Young Adult
chemical_list: D015415:Biomarkers; D007074:Immunoglobulin G