title: Diagnostic Utility of Interleukin-6 Expression by Immunohistochemistry in Differentiating Castleman Disease Subtypes and Reactive Lymphadenopathies.
abstract: The objective of the study was to evaluate the expression pattern of interleukin-6 (IL-6) to determine its utility in differentiating Castleman Disease subtypes and reactive lymphadenopathies. Paraffin-embedded tissue blocks from 20 cases referred for assessment of Castleman Disease (CD) and 4 cases of reactive hyperplasia were selected for immunohistochemical staining with an IL-6 antibody. Six pathologists evaluated the hematoxylin and eosin stained tissue sections and IL-6 expression pattern. Of 20 CD referral cases, the pathologic diagnosis was CD in 14 cases and included 6 hyaline-vascular (HV-CD), 6 plasma cell (PC-CD) and 2 "mixed type"-CD cases. The remaining 6 referral cases showed morphologic features consistent with reactive lymphadenopathy. Patients with non-CD, reactive lymphadenopathies had clinical and/or laboratory features of systemic lupus erythematosus, Hashimoto's disease, viral infection or chronic cellulitis. The pattern of IL-6 expression differed between CD subtypes and non-CD cases. In PC-CD, IL-6 expression was detected in plasma cells and vascular endothelial cells; whereas IL-6 immunoreactivity was detected primarily in vascular endothelial cells in HV-CD. Interfollicular plasma cells were prominent in PC-CD and reactive lymphadenopathies; however, IL-6 expression was significantly increased in PC-CD compared to reactive lymph nodes. Together with morphologic features, the expression pattern of IL-6 detected by immunohistochemistry is helpful to distinguish CD subtypes and reactive mimics.
authors.affiliation: Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, AR, USA gpost@uams.edu.
authors.forename: Ginell R
authors.initials: GR
authors.lastname: Post
authors.affiliation: Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Bell
authors.affiliation: Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
authors.forename: Anwar
authors.initials: A
authors.lastname: Rjoop
authors.affiliation: Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
authors.forename: Rodolfo Henrich
authors.initials: RH
authors.lastname: Lobo
authors.affiliation: Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
authors.forename: Youzhong
authors.initials: Y
authors.lastname: Yuan
authors.affiliation: Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
authors.forename: Steven R
authors.initials: SR
authors.lastname: Post
mesh_terms: D001706:Biopsy; D005871:Castleman Disease / Q000145:classification* / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D015850:Interleukin-6 / Q000378:metabolism*; D008198:Lymph Nodes / Q000473:pathology; D000072281:Lymphadenopathy / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D010950:Plasma Cells / Q000378:metabolism
chemical_list: C508600:IL6 protein, human; D015850:Interleukin-6
keywords: Castleman Disease; Interleukin-6; immunohistochemistry