Immunoglobulin G4–positive ascending thoracic aortitis may be prone to dissection

Abstract

Immunoglobulin (Ig) G4-positive aortitis may determine outcome after surgery for ascending aorta. We evaluated IgG4 expression of dilated ascending aortic wall. The study consisted of 91 patients who underwent ascending aortic surgery. For histology, hematoxylin-eosin, elastase-van Gieson, and periodic acid-Schiff stainings were performed. The amount of T and Blymphocytes, plasma cells, macrophages, cell proliferation, and IgG4 positivity were determined by immunohistochemistry. The aortic wall in 12 patients had IgG4 positivity that was always confined to the adventitia. Adventitial plasma cells were numerous in all but 2 of these patients (P < .0001). Aortitis was revealed in 2 patients (17%) with IgG4-positive staining of the aorta and in 6 patients (8%) with IgG4 negativity. IgG4 staining was significantly associated with total aortic wall inflammation (area under the curve, 0.865; standard error, 0.043; P=.000; 95% confidence interval, 0.779-0.950). The mean diameter of the ascending aorta was 69 ± 4.7 mm and 56 ± 1.1 mm in patients with IgG4 positivity and negativity, respectively (P < .004). Approximately half of the patients with IgG4 positivity had dissection (42%), compared with only 15 of 79 (19%) of the remaining patients (P=not significant). Two patients with IgG4 positivity had to undergo reoperation because of immediate postoperative dissection. Seven patients died, including 4 patients (33%) with IgG4 positivity; the remaining 3 patients (4%) were IgG4 negative (P<.005). IgG4-positive ascending aortic wall was frequent in our study cohort (13%) and revealed aortic inflammation associated with dilatation.