title: IgG4-Related Disease without Overexpression of IgG4: Pathogenesis Implications.
abstract: IgG4-related disease is a new disease group that affects multiple organs. It is characterized by high serum IgG4 and abundant infiltration of IgG4-bearing plasma cells in the affected organ. Here, we describe an intriguing case that suggested that IgG4-related disease might present without IgG4 overexpression or infiltration, at least during a relapse. A 47-year-old man had been diagnosed with systemic lupus erythematosus 15 years. He was admitted due to a pituitary mass, systemic lymphadenopathy, and multiple nodules in the lungs and kidneys. The serum IgG4 level was normal and histopathological examination of the pituitary mass showed abundant lymphocyte and plasma cell infiltration with very few IgG4-positive cells. When we examined specimens preserved from 15 years ago, we found high serum IgG4 levels and IgG4-bearing plasma cell infiltration. This resulted in a diagnosis of IgG4-related disease, and we considered the current episode to be a relapse without IgG4 overexpression. This case indicated that, to clarify the pathogenesis of IgG4-related disease, current cases should repeat specimen evaluations over the course of IgG4-related disease to define diagnostic markers.
authors.affiliation: Division of Rheumatology, Department of Internal Medicine, School of Medicine, Keio University, 35 Shinanomachi Shinjuku-ku, Tokyo 160-8582, Japan.
authors.forename: Naoshi
authors.initials: N
authors.lastname: Nishina
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kaneko
authors.forename: Masataka
authors.initials: M
authors.lastname: Kuwana
authors.forename: Hironari
authors.initials: H
authors.lastname: Hanaoka
authors.forename: Hideto
authors.initials: H
authors.lastname: Kameda
authors.forename: Shuji
authors.initials: S
authors.lastname: Mikami
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Takeuchi