Inflammatory Aneurysm of the Common Iliac Artery With Elevated Serum Levels of Immunoglobulin G4 Manifesting After Endovascular Aneurysm Repair: A Case Report

Inflammatory aneurysms (IAs) are characterized by the thickening of the arterial wall and fibrosis of periarterial tissues. Immunoglobulin G4 (IgG4)-related disease (IgG4-RD) is related to IAs, and about half of IA cases are considered IgG4-related. Although some cases of inflammation after endovascular aneurysm repair (EVAR) have been reported, its relationship with the serum levels of IgG4 has rarely been discussed. Here, we report on a patient diagnosed with and treated for an IA with elevated serum levels of IgG4 following EVAR. An 83-year-old man presented with a bilateral common iliac artery aneurysm. We observed no inflammatory features in his vital signs, laboratory test results, or computed tomography (CT) images. The patient was diagnosed with a non-inflammatory bilateral common iliac artery aneurysm. EVAR was performed using an infrarenal bifurcated stent graft (diameter, 31 mm; length, 15 cm; GORE EXCLUDER AAA Endoprosthesis (WL Gore & Associates, Inc., Flagstaff, AZ, USA)), with an ipsilateral limb stent graft (diameter, 12 mm; length, 7 cm; GORE EXCLUDER) deployed in the left external iliac artery and a contralateral limb stent graft (diameter, 12 mm; length, 14 cm; GORE EXCLUDER) deployed in the right external iliac artery. The patient was discharged in good condition. However, signs of inflammation were observed approximately one month after EVAR. CT images demonstrated the periarterial thickening of the common iliac arteries, and 18F-fluorodeoxyglucose positron emission tomography-CT revealed increased metabolic activity overlying the thickened periarterial tissue. The serum levels of IgG4 and soluble interleukin-2 receptor (sIL-2R) were elevated. The patient underwent steroid therapy based on the suspicion of IgG4-related IA of the common iliac arteries, resulting in reductions of inflammatory signs and periarterial thickening. However, when steroids were reduced, hydronephrosis, periarterial thickening, and increased serum IgG4 and sIL-2R levels were observed. The patient was diagnosed with a relapsed IA and treated with an increased steroid dosage. IAs may occur following EVAR. Steroid therapy may be an effective treatment for post-EVAR IAs, similar to common IAs. Long-term follow-up is desirable to monitor patients for the recurrence of inflammation during the treatment of post-EVAR IAs.