title: IgG4-positive plasma cells in inflammatory pseudotumor (plasma cell granuloma) of the lung.
abstract: The association between IgG4 dysregulation and inflammatory pseudotumor (IPT) was first reported in sclerosing pancreatitis. Recently, we described IPTs of the liver and breast, into both of which many IgG4-positive plasma cells had infiltrated. In this study, we examined the clinical and histological features of 9 cases of IPT (histologically corresponding to plasma cell granuloma) of the lung with an emphasis on IgG4-positive plasma cell infiltration. The lesions were characterized histologically by dense lymphoplasmacytic infiltrates intermixed with fibrosis and, in some cases, prominent eosinophilic infiltration, irregular narrowing of bronchioles entrapped in nodules, and an interstitial pneumonia pattern at the boundaries of nodules. Obliterative phlebitis was easily found in all cases, and 5 lesions also had obliterative arteritis. Immunostaining revealed many IgG4-positive plasma cells diffusely distributed within nodules, and the ratios of IgG4-positive to other plasma cells were extraordinarily high. Of the 9 patients, 8 underwent surgical treatment and in 1 patient, lesion was diagnosed on transbronchial biopsy and effectively treated with corticosteroid. Two cases were associated with chronic sclerosing sialadenitis or lymphadenopathy, in which many IgG4-positive plasma cells were also identified by immunostaining. The clinicopathologic similarities between IPT of the lung and sclerosing pancreatitis suggest that IgG4-related immunopathologic processes might be involved in the pathogenesis of the pulmonary lesions.
authors.affiliation: Department of Human Pathology, Kanazawa University Graduate School of Medicine, Kanazawa 920-8640, Japan.
authors.forename: Yoh
authors.initials: Y
authors.lastname: Zen
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kitagawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Minato
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kurumaya
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Katayanagi
authors.forename: Shinji
authors.initials: S
authors.lastname: Masuda
authors.forename: Hideki
authors.initials: H
authors.lastname: Niwa
authors.forename: Masaki
authors.initials: M
authors.lastname: Fujimura
authors.forename: Yasuni
authors.initials: Y
authors.lastname: Nakanuma
mesh_terms: D000328:Adult; D000368:Aged; D001327:Autoimmune Diseases / Q000276:immunology / Q000473:pathology; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis*; D007150:Immunohistochemistry; D008168:Lung / Q000276:immunology* / Q000473:pathology / Q000601:surgery; D017563:Lung Diseases, Interstitial / Q000276:immunology / Q000473:pathology; D008297:Male; D008875:Middle Aged; D010195:Pancreatitis / Q000276:immunology / Q000473:pathology; D016726:Plasma Cell Granuloma, Pulmonary / Q000276:immunology* / Q000473:pathology / Q000601:surgery; D010950:Plasma Cells / Q000276:immunology* / Q000473:pathology; D016896:Treatment Outcome
chemical_list: D007074:Immunoglobulin G