Distribution of IgG4- and/or IgG-positive plasma cells in Hashimoto's thyroiditis: an immunohistochemical study.
OBJECTIVE
Recently, immunohistochemistry has shown numerous IgG4-positive plasma cells in a subset of Hashimoto's thyroiditis (HT), and this type of HT (IgG4 HT) appears to be a subtype of IgG4-related sclerosing disease. However, little is known about the distribution pattern of plasma cells in IgG4 thyroiditis. To clarify the distribution pattern of IgG4-positive plasma cells, 33 cases of HT demonstrating abundant lymphoplasmacytic infiltrate were studied.


METHODS
Using formalin-fixed paraffin-embedded sections, histological, immunohistochemistry and polymerase chain reaction were performed.


RESULTS
Fourteen cases were classified as IgG4 HT and 19 cases were non-IgG4 HT. Histologically, there was no significant difference between the 2 groups with regard to the degree of stromal fibrosis, lymphoid follicle formation, or the presence of phlebitis or fibrous thyroiditis. The present study demonstrated 2 distribution patterns of IgG4- and/or IgG-positive plasma cells, namely the interfollicular (n = 31) and intrafollicular + interfollicular patterns (n = 2). Interfollicular plasma cells were always polytypic intracytoplasmic immunoglobulin in all 33 cases. However, intrafollicular plasma cells in 2 lesions had monotypic kappa light chain by immunohistochemistry.


CONCLUSIONS
The present study demonstrated that the majority of IgG4 HT and non-IgG HT cases showed an interfollicular distribution pattern of IgG4- and/or IgG-positive plasma cells.
Department of Anatomic and Diagnostic Pathology, Dokkyo University School of Medicine, Mibu, Japan. k-masaru@dokkyomed.ac.jp
Masaru
M
Kojima
Mitsuyoshi
M
Hirokawa
Haruji
H
Kuma
Eijun
E
Nishihara
Nobuhide
N
Masawa
Naoya
N
Nakamura
Akira
A
Miyauchi
D000328:Adult; D000368:Aged; D005260:Female; D050031:Hashimoto Disease / Q000276:immunology* / Q000473:pathology; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis*; D007145:Immunoglobulin kappa-Chains / Q000032:analysis; D007150:Immunohistochemistry; D018655:Lymphocyte Count; D008297:Male; D008875:Middle Aged; D010950:Plasma Cells / Q000276:immunology*; D013961:Thyroid Gland / Q000276:immunology* / Q000473:pathology
D007074:Immunoglobulin G; D007145:Immunoglobulin kappa-Chains