title: Cutaneous multicentric Castleman's disease mimicking IgG4-related disease.
abstract: Castleman's disease, an uncommon lymphoproliferative disorder, can be difficult to differentiate from immunoglobulin (Ig) G4-related disease. The latter is typically characterized by elevated serum IgG4 levels and abundant IgG4-positive cells. However, multicentric Castleman's disease can also have elevated serum IgG4 levels and even fulfill the histological diagnostic criteria for IgG4-related disease. We present a case of cutaneous multicentric Castleman's disease mimicking IgG4-related disease. A 55-year-old Japanese woman developed erythematous and brown plaques on her back. Skin biopsy revealed regressive follicles with interfollicular plasmacytosis, and many plasma cells were positive for IgG4 (mean 263.67±79.19, range 214-355 per high power field). The IgG4-/IgG-positive cell ratios were 35.6%, 36.2%, and 48.4%, respectively, with an average of 40.6%, thus fulfilling the histological diagnostic criteria for IgG4-related disease. Furthermore, serum IgG4 level was significantly elevated (1490 mg/dl; normal range: 4.8-105 mg/dl). However, laboratory findings of anemia, hypoalbuminemia, polyclonal gammaglobulinemia, high C-reactive protein level, and elevated serum interleukin-6 level were consistent with hyper-IL-6 syndrome. Hence, the diagnosis of cutaneous multicentric Castleman's disease was made. In conclusion, IgG4-related disease cannot be differentiated from hyper-IL-6 syndromes on histology alone. Instead, laboratory analyses are necessary to distinguish between the two diseases.
authors.affiliation: Department of Pathology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Kita-ku, Okayama, Japan.
authors.forename: Mai
authors.initials: M
authors.lastname: Takeuchi
authors.forename: Yasuharu
authors.initials: Y
authors.lastname: Sato
authors.forename: Katsuyoshi
authors.initials: K
authors.lastname: Takata
authors.forename: Keita
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Kyotaro
authors.initials: K
authors.lastname: Ohno
authors.forename: Noriko
authors.initials: N
authors.lastname: Iwaki
authors.forename: Yorihisa
authors.initials: Y
authors.lastname: Orita
authors.forename: Tadashi
authors.initials: T
authors.lastname: Yoshino
mesh_terms: D001327:Autoimmune Diseases / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D005871:Castleman Disease / Q000097:blood / Q000175:diagnosis* / Q000188:drug therapy / Q000276:immunology; D003937:Diagnosis, Differential; D005260:Female; D005938:Glucocorticoids / Q000627:therapeutic use; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D008875:Middle Aged; D010950:Plasma Cells / Q000378:metabolism / Q000473:pathology; D012871:Skin Diseases / Q000097:blood / Q000175:diagnosis* / Q000188:drug therapy / Q000276:immunology; D016896:Treatment Outcome
chemical_list: D005938:Glucocorticoids; D007074:Immunoglobulin G