Large Isolated Hypogastric Artery Aneurysm Compressing Both Pelvic Ureters
Article Outline
Abstract
We report an unusual case of an isolated, large, thrombosed hypogastric artery aneurysm presenting as a voluminous pelvic mass with bilateral hydroureteronephrosis. The patient underwent successful surgical removal of the mass. Histology confirmed an aneurysm of the left hypogastric artery.
Keywords: Pelvic mass, Hypogastric aneurysm, Urological symptoms
Isolated hypogastric artery aneurysms are rare.1 In a review of 671 patients with abdominal aneurysm, Silver et al. found only three (0.4%) isolated internal iliac artery aneurysms.2 At diagnosis, such aneurysms may be asymptomatic or present symptoms generally due to the compression of adjacent organs.1 We report an unusual case of an isolated giant internal iliac artery aneurysm entirely thrombosed, presenting as a voluminous pelvic mass causing bilateral hydroureteronephrosis.
Report
A 71-year-old male patient suffering from arterial hypertension, with no previous history of trauma or pelvic surgery presented with renal impairment and a pelvic mass. Laboratory tests revealed increased renal function test but normal tumour markers. On abdominal examination, a voluminous, non-pulsatile mass was palpable in the left side of the abdomen. About 7 years earlier, the patient had manifested a mass in the hypogastric region and a computed tomography (CT) scan demonstrated a pelvic mass of an unclear origin and nature. The tests carried out did not allow a firm diagnosis. The patient was told that a definite diagnosis was only possible by surgery and a histological examination. The patient was also informed of the risks involved regarding the various diagnostic options and the foregoing of surgery. However, the patient refused to undergo surgery, preferring, instead, regular CT scans and accepting the risks involved in such a choice. Periodical radiographs showed a progressively increasing volume of the lesion. By 2006, it was so large that it was visible at the clinical abdominal examination.
The patient also underwent abdominal ultrasound, which added no further useful diagnostic information to that already provided by the CT scan. Both the ultrasound and the CT scan showed the presence of calcification within the mass; this finding however did not furnish a certain diagnosis. Moreover, the ultrasound did not show the presence of peri-lesional collateral small vessels. In January 2007, a diagnosis was made of severe bilateral hydroureteronephrosis secondary to ureteral stenosis from compression, and bilateral percutaneous nephrostomy was performed.
The patient came to us in May 2007 with a suspected diagnosis of a benign lesion, in view of the long clinical history. Further CT and MRI scans failed to clarify the picture due to the complete lack of uptake of the contrast medium inside the lesion. A three-dimensional (3D) CT scan demonstrated an indistinct mass appearing as a radiological blank, of enormous size, localised between the two hypogastric arteries (Fig. 2). In the 3D reconstruction (arterial phase), the mass is not visible as it did not take up contrast, and so the two hypogastric arteries are visible (Fig. 1). In the small image, it is possible to see the large abdominal distension due to the presence of the voluminous neo-formation.
Figure 1
Figure 2
At this point, the patient agreed to undergo surgery. During the procedure, after identification and isolation of left iliac vessels, the mass was isolated, opened and then resected.
Histological examination of the external wall confirmed the aneurysmatic nature of the lesion. The patient was discharged on the 8th postoperative day and, after 12 months follow-up, he is in good general conditions despite an irreversible bilateral uretal stenosis. CT scans at 1 year demonstrated the eradication of the lesion but confirmed irreversible stenosis of the two ureters in the pelvic region. The patient is awaiting surgical re-implantation of the ureters in the bladder.
Discussion
Isolated aneurysms of the internal iliac artery are uncommon.2 They generally measure 3–8
cm in diameter and are more frequent in men, the male–female ratio being 6:1.3 They occur predominantly in men over the age of 60 years.2 The main cause of isolated aneurysm of the internal iliac artery is atherosclerosis, infection, trauma and disorders of the arterial wall, but the majority of cases are related to progressive atherosclerosis.1 Early diagnosis is difficult when the aneurysm is small because it is asymptomatic, but it is even more difficult when it is large and without collateral vessels, as in our case, because it is non-pulsatile and there is poor uptake of contrast medium at CT scan due to complete thrombosis of the aneurysm.4
An isolated internal iliac artery aneurysm may be asymptomatic at diagnosis, present with frank rupture or present with symptoms caused by compression of adjacent organs such as the ureters.1 The compression symptoms are not pathognomonic and so it is difficult to differentiate an aneurysm, when completely full of thrombi and not pulsatile, from common large pelvic masses such as tumours, abscesses and haematomas.5 Urological symptoms such as ureteric colic, hydroureteronephrosis, pyelonephritis and renal failure are common and secondary to ureteral obstruction. Ureteral stenting or, as in our case, percutaneous nephrostomy prior to elective surgical repair may improve the renal function.
The natural history of this aneurysm is unclear, but probably is one of increasing size, associated with increasing risk of rupture. In the study by Richardson and Greenfield, the mean size of IIIAA at diagnosis was 7.7cm with a 33% incidence of rupture, although the mean size of ruptured aneurysm was 5.6cm.6 In a study by Brin and Busuttil, rupture occurred in 38% with a mortality of 58% although they could not find a direct relationship between the size of the aneurysm and the risk of rupture.3
Rupture of the aneurysm may be the first presentation; in this case, the symptoms are hypotension, abdominal groin and thigh pain. Retroperitoneal rupture may be contained but intraperitoneal can lead to rapid death. Rupture into the rectum, ureter and bladder have all been reported. When rupture occurs, mortality usually ranges from 50% to 100%.1
Ultrasound, CT and magnetic resonance imaging (MRI) are the most indicated diagnostic tools in the case of aneurysms, especially with the use of contrast medium. CT scan with contrast medium shows the aneurysm site, size and relationship to other organs and is recommended for elective repair.7
The criteria for repair of asymptomatic aneurysm are a size greater than 3cm, depending on the age of the patient, and associated co-morbidities.8 Surgery is recommended by most authors and should be performed as soon as the diagnosis is made. Elective surgical intervention has a mortality of less than 10%, while mortality as high as 80% has been reported with attempts at surgical repair after rupture.5
There has been some evolution in surgical treatment over the year. Proximal ligation of the internal iliac artery is the oldest procedure, but carries a recurrence rate up to 33%.2 Proximal and distal ligation with insertion of an interposition graft is indicated when the contralateral internal iliac artery is occluded or when bilateral internal iliac aneurysms are being repaired.9 Proximal control and endo-aneurysmal ligation involves over-sewing the individual collateral vessels from within the aneurysm sac. This is the treatment of choice for an isolated internal iliac artery aneurysm with a normal contralateral internal iliac artery.9
Aneurysm can now be treated successfully by transcatheter arterial embolisation with or without the use of a stent.10
The present case report features a number of peculiarities that are worthy of note. The long clinical history of the lesion made it possible to exclude a malignant origin of the disease, although the lack of contrast medium uptake did not allow us to formulate a firm diagnosis.
In the light of the operative findings, it can be hypothesised that that the aneurysm lay in intermittent continuity with the vascular lumen, associated with a constant, rapid endocavitary blood thrombosis process. This condition, which was not treated because the patient refused to undergo any treatment, resulted in continual growth of the lesion until it reached the giant size found at surgery. Surgery appeared to be the only feasible option in view of the uncertain preoperative diagnosis and the enormous size of the mass.
References
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- . Isolated internal iliac aneurysm presenting as giant pelvic masses. AJR. 1983;140:784–786
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- . Isolated iliac artery aneurysm. Surgery. 1983;93(5):688–693
- . Aneurysm of the internal iliac artery: management strategy. Ann Vasc Surg. 2001;15(3):321–325
- . Bilateral isolated internal iliac aneurysm presenting as pelvic tumors. Rontgenblatter. 1987;40(11):360–362
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PII: S1533-3167(09)00029-6
doi:10.1016/j.ejvsextra.2009.09.001
© 2009 European Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.
Refers to article:
- Large Isolated Hypogastric Artery Aneurysm Compressing Both Pelvic Ureters , 19 October 2009
