Postoperative Course of Inflammatory Abdominal Aortic Aneurysms

Of 779 patients undergoing repair of abdominal aortic aneurysms over a 7-year period (1984-1990), 40 (5.1%) had gross features of inflammatory abdominal aortic aneurysms (IAAAs). Twenty IAAAs were assessed by CT scan preoperatively and postoperatively to evaluate the outcome of the inflammatory layer of the aneurysm in 19 cases. Complete postoperative regression was observed in nine cases (47.3%), partial regression in four (21%), and stable lesions in six (31.7%). No roentgenographic progression was found. The comparison between the roentgenologic outcome and preoperative clinical features (age, sex, erythrocyte sedimentation rate, and abdominal lumbar pain), pathologic findings, and follow-up time revealed a significant correlation (p < 0.05) between the postoperative outcome and the histologic findings in the wall (cell density and cell/fibrosis ratio). Complete regression of inflammation was observed when high cell density (16 +/- 0.7 cells/2116 microns 2) and a cell/fibrosis ratio > 1 were found. On the contrary, little or no regression of inflammation occurred when a low cell density (3.4 +/- 0.3 cells/2116 microns 2) and a cell/fibrosis ratio < 1 were found. Although it is generally thought that inflammation in IAAAs regresses after surgical repair, in our study, 31.7% of the postoperative CT scans showed no change. Histologically, the variability of morphologic aspects seemed to correlate with the relative proportions of cellular infiltrate and interstitial fibrosis in the aneurysmal wall. These proportions determine the postoperative course of the inflammation layer and, most likely, the response of the latter to steroid therapy as well.