Surgical Pathology of Aortic Aneurysms Associated with Non-Infectious Inflammation (1994-2011): The Role of IgG4
Mathieu C Castonguay, Jorge E Rocha, William D Edwards, Joseph J Maleszewski. Mayo Clinic, Rochester, MN
Background: The increasingly recognized roleS that IgG4-related sclerosing diseases (IgG4-RSD) play in the development of aortic aneurysms has raised many questions regarding our understanding and classification of both thoracic and abdominal aortic aneurysms. Recently, investigators have suggested that a significant proportion of so-called “inflammatory aortic aneurysms” are associated with increased IgG4-reactive plasma cells, though definitive criteria have yet to be established.
Design: A retrospective clinicopathologic review was undertaken of surgically resected aortic aneurysms associated with varying degrees inflammation. The study groups included 42 cases. Clinical records were reviewed to document the presence of traditional risk factors associated with aortic aneurysms and for the presence of other IgG4-RSD. Archived H&E- and Verhoeff-van Gieson-stained slides were reviewed to evaluate the type of aneurysm and the location and composition of the inflammatory infiltrate. Immunohistochemical studies evaluating the density and proportion of plasma cells expressing IgG4 (as a proportion of plasma cells expressing IgG) were undertaken.
Results: The forty-two patients ranged in age from 19 to 84 years. Thirty were men. Aneurysms were classified as “inflammatory aneurysms” (27 cases) and included inflammatory abdominal aortic aneurysms (AAA) and 1 inflammatory thoracic aortic aneurysm, and others, included atherosclerotic aneurysms with inflammation insufficient to qualify as inflammatory AAA (6 cases), those associated with aortitis (6 cases), and those associated with medial degeneration (3 cases). Age, sex, and traditional risk factors for atherosclerotic aneurysms did not differ between groups. Adventitial inflammation occurred more frequently in inflammatory aneurysms (p<0.05), but the proportion and density of plasma cells expressing IgG4 did not vary significantly. Additional features, such as reactive lymphoid follicles, phlebitis, and medial inflammation, did not differ between groups. 16 aneurysms had >100 IgG-positive plasma cells per high-power field; 11 of these were “inflammatory aneurysms." The average IgG4 proportion did not differ between these two groups (30.86% vs. 48.51%, respectively; p=0.16).
Conclusions: Our data does not support the contention that inflammatory aneurysms are more frequently associated with an increased proportion of IgG4-expressing plasma cells than other aneurysms with inflammation. In fact, the proportion of IgG4-positive plasma cells was less in inflammatory aneurysms, although this did not reach statistical significance.
Wednesday, March 21, 2012 1:00 PM
Poster Session VI # 42, Wednesday Afternoon