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Answer: Internal Iliac Artery Aneurysm
Isolated internal iliac artery aneurysms are rare with an estimated incidence of 0.4%.1 Internal iliac artery aneurysms are often large at the time of diagnosis resulting in compression of adjacent structures.2 Indeed, the natural history of internal iliac artery aneurysms is generally considered to involve an increase in size with eventual rupture, with an incidence reported as high as 38%.3
Multiple modalities exist for the management of these aneurysms and include simple ligation, excision, aneurysmorrhaphy, and embolization, as well as exclusion with a covered stent.1 They can pose a technical challenge in gaining distal control during open surgery secondary to their deep location within the pelvis.1 Our patient had multiple previous attempts at coil embolization as well as ligation that failed resulting in massive aneurysm enlargement. He had initially undergone infrarenal aortic aneurysm repair with a bifurcated conventional graft undoubtedly leaving behind residual iliac aneurysmal disease.
This experience supports continued surveillance of patients having residual iliac aneurysmal involvement. Indeed, several studies have described the progression of aortoiliac aneurysmal disease after aortic reconstruction. Most of these studies concern patients who initially underwent tube graft repair of infrarenal aortic aneurysms with varying degrees of iliac involvement at the time of initial operation. In a study by Adam et al,4 1.4% of patients undergoing aortic tube graft repair for infrarenal aortic aneurysms had progression of their disease over 5 to 112 months of follow-up. Hassen-Khodja et al5 described the need for repeated operative intervention for iliac artery aneurysm progression in 2% of their study population who had all previously undergone aortic reconstruction with an infrarenal tube graft. Although the number of patients experiencing progression of iliac aneurysmal disease after open aortic reconstruction appears small, surveillance seems appropriate secondary to the potential grave complications up to and including rupture. As evidenced by our patient, late failure of endovascular exclusion and coiling of internal iliac aneurysms needs consideration and imaging follow-up. Late events after aneurysm coiling can be anticipated based on the known risks of failure and can be identified through a structured clinical follow-up program.
In regard to our patient, initial plans to biopsy the mass were changed after a vascular surgery consult was obtained and review of computed tomographic scans from 5 and 2 years previously and the current scan (Figure 1 and Figure 2) was accomplished. The conclusion was that this represented an internal iliac artery aneurysm that measured 13.6 cm in diameter. Left internal iliac artery aneurysmorrhaphy with ligation of the gluteal and pudendal arteries, as well as the ostium of the left internal iliac artery, was performed. The postoperative course was complicated by a prolonged ileus, which resolved with recovery.
Computed tomographic scan of the pelvis shows a large, homogeneous mass with a metallic density at the periphery.
Computed tomographic scan in sagittal view shows the cephalad extension of the mass out of the pelvis.
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Correspondence: Thomas C. Naslund, MD, Division of Vascular Surgery, Vanderbilt University Medical Center, 1161 22nd Ave South, D-5237 Medical Center North, Nashville, TN 37232-2735 (email@example.com).
Accepted for Publication: July 6, 2009.
Author Contributions:Study concept and design: Irwin and Naslund. Acquisition of data: Irwin. Analysis and interpretation of data: Irwin and Naslund. Drafting of the manuscript: Irwin and Naslund. Critical revision of the manuscript for important intellectual content: Naslund. Administrative, technical, and material support: Irwin. Study supervision: Naslund.
Financial Disclosure: Dr Naslund has received reimbursement for consulting for W. L. Gore & Associates and Boston Scientific; reimbursement/stock options (<$10 000 value) for being on the scientific advisory board for LeMaitre Vascular; and compensation for consulting for CVRx and Boston Scientific.
Image of the Month—Diagnosis. Arch Surg. 2010;145(9):912. doi:10.1001/archsurg.2010.168-b
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