title: Case of immunoglobulin G4-related skin disease: possible immunoglobulin G4-related skin disease cases in cutaneous pseudolymphoma only by immunohistochemical analysis.
abstract: Immunoglobulin G4-related disease (IgG4-RD) is a newly recognized disease characterized by elevated serum IgG4 levels, tissue infiltration rich in IgG4(+) plasma cells. We report on a case which was first considered as pseudolymphoma from the histopathological analysis, but finally diagnosed as IgG4-related skin lesions. As the morphological features of cutaneous involvement of IgG4-RD are consistent with those of cutaneous pseudolymphoma, we tried immunostaining past potential cases of IgG4-RD. Thirty-two skin specimens (15 men and 17 women; mean age, 53 years) diagnosed as having pseudolymphoma were retrieved from the archives to conduct hematoxylin-eosin, IgG and IgG4 staining. Out of the 32 cases of cutaneous pseudolymphoma, germinal center formation was seen in 22 cases, and moderate-severe fibrosis was seen in seven cases. Eleven cases showed more than 10 IgG4(+) plasma cell infiltration/high-power field, and among these 11 cases, seven cases (22%) showed A ratio of IgG4(+)/IgG(+) cells of more than 40%. Thus, out of the 32 cases of cutaneous pseudolymphomas, two cases (6.3%) satisfied IgG4-RD histopathological diagnostic criteria. As clinical presentations and histopathological features of skin involvement of IgG4-RD are analogous to cutaneous B-cell pseudolymphoma, careful identification is required through systemic examination, serum IgG4 measurement and other means.
authors.affiliation: Department of Dermatology, Fujita Health University School of Medicine, Toyoake, Japan.
authors.forename: Yohei
authors.initials: Y
authors.lastname: Iwata
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Mizoguchi
authors.forename: Masayuki
authors.initials: M
authors.lastname: Takahashi
authors.forename: Beni
authors.initials: B
authors.lastname: Tanaka
authors.forename: Makoto
authors.initials: M
authors.lastname: Kuroda
authors.forename: Akiko
authors.initials: A
authors.lastname: Yagami
authors.forename: Kayoko
authors.initials: K
authors.lastname: Matsunaga
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D019310:Pseudolymphoma / Q000175:diagnosis* / Q000276:immunology / Q000378:metabolism; D012189:Retrospective Studies; D012871:Skin Diseases / Q000175:diagnosis* / Q000276:immunology / Q000378:metabolism; D055815:Young Adult
chemical_list: D007074:Immunoglobulin G
keywords: diagnosis; immunoglobulin G4; immunoglobulin G4-related diseases; immunohistochemistry; pseudolymphoma