title: Immunohistochemical analysis of IgA expression differentiates IgG4-related disease from plasma cell-type Castleman disease.
abstract: Plasma cell-type Castleman disease (PCD) is often encountered when differentiating IgG4-related disease (IgG4-RD). Given that serum IgA is often elevated in Castleman disease, we investigated whether IgA expression levels in histological specimens can be used to differentiate between the two diseases. Lymph node lesions obtained from 12 IgG4-RD and 11 PCD patients were analysed by immunohistochemistry with anti-IgG, -IgG4, and -IgA antibodies. In addition to all 12 cases of IgG4-RD, 8/11 cases (72.7 %) of PCD also met the diagnostic criteria of IgG4-RD (serum IgG4 ≥135 mg/dl and IgG4/IgG-positive cells ≥40 %). IgA-positive cells were sparsely and densely distributed in IgG4-RD and PCD cases, respectively. The median number of IgA-positive cells ± SD in all 12 cases of IgG4-RD was 31 ± 37 cells per three high-powered fields (3HPFs) (range 4-118 cells/3HPFs). In contrast, the median number of IgA-positive cells, which was significantly higher in all 11 cases of PCD, was 303 ± 238 cells/3HPFs (range 74-737 cells/3HPFs) (P < 0.001). In conclusion, our findings indicate that in cases where serum analysis-based data are unavailable, anti-IgA immunostaining can be used for differential diagnosis of IgG4-RD.
authors.affiliation: Department of Pathology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1, Shikata-cho, Kita-ku, Okayama, 700-8558, Japan.|Department of Clinical Laboratory, Fukuyama City Hospital, Fukuyama, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Manabe
authors.affiliation: Department of Pathology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1, Shikata-cho, Kita-ku, Okayama, 700-8558, Japan.
authors.forename: Takuro
authors.initials: T
authors.lastname: Igawa
authors.affiliation: Department of Pathology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1, Shikata-cho, Kita-ku, Okayama, 700-8558, Japan.
authors.forename: Mai
authors.initials: M
authors.lastname: Takeuchi
authors.affiliation: Department of Pathology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1, Shikata-cho, Kita-ku, Okayama, 700-8558, Japan.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Gion
authors.affiliation: Department of Pathology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1, Shikata-cho, Kita-ku, Okayama, 700-8558, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Yoshino
authors.affiliation: Department of Pathology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1, Shikata-cho, Kita-ku, Okayama, 700-8558, Japan. satou-y@okayama-u.ac.jp.|Division of Pathophysiology, Okayama University Graduate School of Health Sciences, Okayama, Japan. satou-y@okayama-u.ac.jp.
authors.forename: Yasuharu
authors.initials: Y
authors.lastname: Sato
mesh_terms: D000328:Adult; D000368:Aged; D005871:Castleman Disease / Q000097:blood / Q000175:diagnosis*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000378:metabolism*; D007074:Immunoglobulin G / Q000097:blood / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D010950:Plasma Cells / Q000473:pathology*; D012372:ROC Curve
chemical_list: D007070:Immunoglobulin A; D007074:Immunoglobulin G
keywords: Hyper IL-6 syndrome; IgG4; IgG4-related disease; Immunohistochemistry; Plasma cell type Castleman disease