The microscopic features of inflammatory abdominal aortic aneurysms: discriminant analysis

Abstract

Up to 15% of abdominal aortic aneurysms are designated as inflammatory. They are characterized by marked fibrous thickening of the aneurysmal wall, with the fibrosis extending into the adjacent retroperitoneum. Thirty-five abdominal aortic aneurysms were studied, 15 inflammatory and 20 atherosclerotic. Of the inflammatory group, 10 were symptomatic and five asymptomatic. For each resection specimen, 59 microscopic features (variables) were scored semi-quantitatively. Discriminant function analysis showed that endarteritis obliterans, fibrosis around nerves or ganglia at the outer margin of mural fibrosis, and the thickness of the combined fibrotic media and adventitia gave a satisfactory high discrimination between atherosclerotic and inflammatory aneurysms. When these three variables are used together, a histological diagnosis of inflammatory aneurysm can be made with an expected accuracy in excess of 80%.

Consensus statement on surgical pathology of the aorta from the Society for Cardiovascular Pathology and the Association for European Cardiovascular Pathology: I. Inflammatory diseases

“…Eosinophils may also be present. It is recommended that, for a pathologic diagnosis of IAA, the thickness of the aortic wall exceeds 4 mm [13]. The primary entity in the differential is periaortitis.…”

“…Inflammatory aortic aneurysm or IAA is a disorder identified initially based on the intraoperative gross appearance of the aorta showing thickening of the wall with fibrosis and extensive adhesions to adjacent structures [13,28,[33][34][35][36][37][38][39][40][41]. So defined, it has been reported to be present in 2%-15% of resected abdominal aortic aneurysms, most often in men, and usually in the setting of severe aortic atherosclerosis.…”

“…Since the condition is often defined clinically or intraoperatively, these cases likely represent a mixture of diseases ranging from secondary complications of severe atherosclerosis to primary involvement by systemic rheumatologic diseases. In some series, the pathologic features of inflammatory aneurysm, as defined intraoperatively, overlap with the pathologic features of atherosclerosis [13,28,35,40,41]. In patients with clinically defined IAA, inflammatory markers elevated preoperatively have been reported to normalize after repair of the aneurysm, despite the aneurysm tissue not being resected.…”

Inflammatory Abdominal Aortic Aneurysm Followed by Disseminated Intravascular Coagulation and Immune Thrombocytopenia.

“…Adherence of surrounding visceral structures, the ureter, duodenum, vena cava, and renal veins to the periaortic inflammatory mass are characteristics of the IAAA, and patients frequently complain of back or flank pain (1-5). Histopathologically there is a chronic inflammation of connective tissues with infiltrates of lympho- cytes and plasma cells (1,5,13). The disease should be differentiated from idiopathic retroperitoneal fibrosis (IRF) ( 1 2, 14).…”

“…In July 1993, a computed tomographic (CT) scan of the chest, gallium scintigraphy, and bronchofiberscopic transbronchial lung biopsy revealed idiopathic interstitial pneumonia (IIP). His platelet count was 13.6x1OVjliI at that time. A CT scan of the abdomen revealed AAA.During 3 years of outpatient follow-up at the hospital, occasional transient mild thrombocytopenia, and elevated fibrin/fibrinogen degradation product (FDP) and D-Dimer were observed.…”