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Int J Clin Exp Pathol 2013;6(3):469-475

Original Article
Inflammatory aortic aneurysm: possible manifestation of IgG4-related sclerosing disease

Kirtee Raparia, Claudia P Molina, Gabriela Quiroga-Garza, Donald Weilbaecher, Alberto G Ayala, Jae Y Ro

Departments of Pathology, Northwestern University, Chicago, IL and The Methodist Hospital, Houston, TX

Received December 7, 2012; Accepted January 11, 2013; Epub February 15, 2013; Published March 1, 2013

Abstract: In this study, we investigate the hypothesis that IgG4-related autoimmune reaction is involved in the formation of inflammatory aortic
aneurysms. We obtained 23 cases of IAA and 11 cases of atherosclerotic aortic aneurysms (AAA) as control group. We evaluated the
expression of IgG4 in both IAA study cases and AAA control cases. In addition, immunohistochemical expression of C-Kit, CD21, CD34, S-100
protein, SMA, vimentin, p53, beta-catenin, and ALK-1, and EBV-LMP1 expression by in situ hybridization were performed only in IAA cases. Of
the 23 patients, 20 were males and 3 were females (M: F ratio 6.7:1); age ranged from 43 to 81 years (average 64.3 years). Histologically, all 23
cases of IAA formed a mass that displayed inflammatory myofibroblastic tumor-like features. All lesions stained strongly and diffusely for
vimentin and SMA (100%); 17 stained strongly and focally for CD34 (74%); and all were negative for C-Kit, CD21, S-100 protein, p53, beta-
catenin, EBV-LMP1, and ALK-1. The numbers of infiltrating IgG4-positive plasma cells in IAA cases exceed that of AAA cases. Score 3 (>50
plasma cells/one 40X field) of IgG4-positive plasma cells was only seen in IAA cases (13/23, 57%), whereas none of the 11 cases of AAA
showed score 3 IgG4-positive plasma cells (P=0.0018, Fischer‘s exact test). Our findings suggest that IAA may be an aortic manifestation of
the IgG4-related sclerosing disease. The high number of positive plasma cells, >50 plasma cells/one 40X field is more specific for the IAA than
for AAA; however, lesser number can be seen in both IAA and AAA patients. (IJCEP1212012).

Keywords: Inflammatory aortic aneurysms, IgG4 related sclerosing disease, immunohistochemistry

Address correspondence to: Dr. Jae Y Ro, Professor and Director of Surgical Pathology, Department of Pathology and Genomic Medicine, The
Methodist Hospital, Weill Medical College of Cornell University, 6565 Fannin Street, M227, Houston, TX 77030. Phone: 713-441-2263; Fax: 713-
793-1603; E-mail: jaero@tmhs.org