Immunohistochemistry of IgG4 can help subclassify Hashimoto's autoimmune thyroiditis
Version of Record online: 13 AUG 2009
© 2009 The Authors. Journal compilation © 2009 Japanese Society of Pathology
Volume 59, Issue 9, pages 636–641, September 2009
How to Cite
Li, Y., Bai, Y., Liu, Z., Ozaki, T., Taniguchi, E., Mori, I., Nagayama, K., Nakamura, H. and Kakudo, K. (2009), Immunohistochemistry of IgG4 can help subclassify Hashimoto's autoimmune thyroiditis. Pathology International, 59: 636–641. doi: 10.1111/j.1440-1827.2009.02419.x
- Issue online: 13 AUG 2009
- Version of Record online: 13 AUG 2009
- Received 1 December 2008. Accepted for publication 7 May 2009.
- autoimmune disease;
- plasma cell;
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.