Clinicopathological analysis of enlarged abdominal aortic aneurysms after endovascular aneurysm repair and the relationship with occult IgG4-related vascular disease.

Purpose: To evaluate the incidence of IgG4-related vascular disease (IgG4-VD) in aneurysm enlargement after endovascular aneurysm repair (EVAR).

Methods: Of 1482 EVAR cases in which patients underwent initial treatment at our hospital, 33 patients who underwent open surgery for an enlarged aneurysm were retrospectively identified. Histopathological examination of the aneurysm wall specimens was performed and the relationship of the histopathological findings with IgG4-VD was investigated.

Results: The median aneurysm diameter at EVAR was 53 mm (interquartile range [IQR] 50-55), and the aneurysm diameter at open surgery was 79 mm (IQR 75-88). Six patients (18%) were histopathologically diagnosed with IgG4-VD. Relative to the non-IgG4-VD cases, the patients with IgG4-VD had a higher incidence of coronary artery disease (83% vs. 30%, p = 0.015) and greater aneurysm wall thickness at the time of open surgery (2.4 mm vs. 1.6 mm, p < 0.001). Serum IgG4 levels were significantly higher in patients with IgG4-VD than in those without IgG4-VD (218 mg/L vs. 46 mg/L, p = 0.002).

Conclusions: IgG4-VD was found in 18% cases with enlarged aneurysms after EVAR. If aneurysm enlargement is observed after EVAR, measurement of the aneurysm wall thickness using preoperative CT angiography and the evaluation of serum IgG4 levels could be useful for diagnosing occult IgG4-VD.