Pathological Features of Adventitial inflammatory Reaction in Acute Aortic Dissections
Lauren F Xu, Carlen Miller, Allen P Burke. University of Maryland Medical Center, Baltimore, MD
Background: Histological reaction in the adventitia to aortic dissections has not been well studied. We present histological findings in a series of acute aortic dissections with emphasis regarding dating and inflammatory reaction.
Design: We prospectively studied 43 surgically excised acute ascending aortic dissections. We evaluated the histological reaction in the media and adventitia adjacent to the acute dissection plane in 4 or more sections of aorta oriented perpendicularly. Inflammation (both degree and type) and stromal reaction were semiquantitated and correlated with duration of symptoms prior to surgical repair.
Results: Of the 43 cases, there were 31 men (ages 53 ± 14 years) and 13 women (ages 60 ± 17 years). Duration of symptoms was classified as <12 hours (n= 9), 12-24 hours (n=12), 1-2 days (n=8), 2-7 days (n=11), and > 1 week (n=3). Medial inflammation was usually relatively sparse. When present, neutrophils were detected within 12 hours, and in one case there was intense medial inflammation suggestive of aortitis. Lymphocytes were present after 12 hours, and macrophages were present after 1 day and peaked between 2-7 days. Lymphocytes and macrophages were observed in 80% of cases occurring in this time frame, and were numerous in 3 cases mimicking vasculitis.
Comparatively, adventitial inflammation was relatively brisk. Neutrophils occurred before 12 hours, peaked between 12-24 hours, and were rare after 2 days. Eosinophils occurred after 1 day, peaked between 2-7 days, and were predominant in 3 cases between 2-7 days. Apoptosis occurred after 12 hours, peaked between 1-2 days; mitotic figures were present in similar time frame as apoptosis, but were still numerous up to 7 days. Macrophages followed by reactive fibroblasts were present after 1 day and peaked 2-7 days. Prominent inflammation of adventitial nerves and proliferation of paraganglial cells were observed in 7 cases; these cases showed neural influx of atypical macrophages and stromal cells. Hemosiderin-laden macrophages were present only in one case, which had a concomitant healed dissection.
Conclusions: Reactive changes in the adventitia and media are fairly reliable, and can be used to date aortic dissections in the first week after medial rupture. Inflammatory reaction in the media can occasionally contain numerous neutrophils, lymphocytes, or macrophages, mimicking vasculitis, and eosinophils may be prominent in the adventitia.
Wednesday, March 21, 2012 1:00 PM
Poster Session VI # 44, Wednesday Afternoon