Cutoff Values of Serum IgG4 and Histopathological IgG4+ Plasma Cells for Diagnosis of Patients with IgG4-Related Disease.
IgG4-related disease is a new disease classification established in Japan in the 21st century. Patients with IgG4-related disease display hyper-IgG4-gammaglobulinemia, massive infiltration of IgG4+ plasma cells into tissue, and good response to glucocorticoids. Since IgG4 overexpression is also observed in other disorders, it is necessary to diagnose IgG4-related disease carefully and correctly. We therefore sought to determine cutoff values for serum IgG4 and IgG4/IgG and for IgG4+/IgG+ plasma cells in tissue diagnostic of IgG4-related disease. Patients and Methods. We retrospectively analyzed serum IgG4 concentrations and IgG4/IgG ratio and IgG4+/IgG+ plasma cell ratio in tissues of 132 patients with IgG4-related disease and 48 patients with other disorders. Result. Serum IgG4 >135  mg/dl demonstrated a sensitivity of 97.0% and a specificity of 79.6% in diagnosing IgG4-related disease, and serum IgG4/IgG ratios >8% had a sensitivity and specificity of 95.5% and 87.5%, respectively. IgG4+cell/IgG+ cell ratio in tissues >40% had a sensitivity and specificity of 94.4% and 85.7%, respectively. However, the number of IgG4+ cells was reduced in severely fibrotic parts of tissues. Conclusion. Although a recent unanimous consensus of all relevant researchers in Japan recently established the diagnostic criteria for IgG4-related disease, findings such as ours indicate that further discussion is needed.
Hematology and Immunology, Kanazawa Medical University, 1-1 Daigaku, Uchinada, Kahoku-gun, Ishikawa 920-0293, Japan.
Yasufumi
Y
Masaki
Nozomu
N
Kurose
Motohisa
M
Yamamoto
Hiroki
H
Takahashi
Takako
T
Saeki
Atsushi
A
Azumi
Shinji
S
Nakada
Shoko
S
Matsui
Tomoki
T
Origuchi
Susumu
S
Nishiyama
Kazunori
K
Yamada
Mitsuhiro
M
Kawano
Akira
A
Hirabayashi
Keita
K
Fujikawa
Tomoko
T
Sugiura
Masanobu
M
Horikoshi
Naoto
N
Umeda
Hiroshi
H
Minato
Takuji
T
Nakamura
Haruka
H
Iwao
Akio
A
Nakajima
Miyuki
M
Miki
Tomoyuki
T
Sakai
Toshioki
T
Sawaki
Takafumi
T
Kawanami
Yoshimasa
Y
Fujita
Masao
M
Tanaka
Toshihiro
T
Fukushima
Katumi
K
Eguchi
Susumu
S
Sugai
Hisanori
H
Umehara