An unusual enemy: Case report of a giant splenic artery pseudoaneurysm of unknown etiology in a young soldier

Introduction

Splenic artery pseudoaneurysms^a (SAPA) are rare, with overall incidence reported at 0.01–0.2 % per 100,000. There are only around 200 cases described in the literature to date. The splenic artery is the most common site for a pseudoaneurysm, accounting for 46 % of visceral artery pseudoaneurysms. They occur more commonly in males, with risk factors including pancreatitis, trauma, and iatrogenic injuries from pancreatic surgery. Pseudoaneurysms can be symptomatic, and symptoms can include vague abdominal pain, hematochezia, melena, or hematemesis. Sizes of splenic artery pseudoaneurysms can vary from 0.3 to 17 cm, with lesions greater than 5 cm classified as giant pseudoaneurysms, which are very rare. Diagnosis is typically made with a computed tomography angiography^b (CTA), which shows a contrast-filled vessel wall outpouching. Because risk of rupture can reach 47 % and this risk is unrelated to the size of the pseudoaneurysm, all pseudoaneurysms should be treated. Failure to intervene resulting in rupture can result in a mortality reaching 90 %. Endovascular interventions are the preferred treatment; however, if the patient is unstable, open ligation of the lesion is required.

Methods

A 35-year-old active-duty male with no history of abdominal trauma was transferred to our facility after a 12 cm splenic artery pseudoaneurysm was found incidentally on computed tomography^c (CT) scan performed for elevated liver enzymes during a hospitalization for new-onset diabetes. This CT also demonstrated new findings of two suspected pancreatic intraductal papillary mucinous neoplasms^d (IPMN), but no evidence of pancreatitis. He denied abdominal pain, nausea, vomiting, and changes in bowel habits. The patient's physical exam was unremarkable and vital signs were within normal limits. Laboratory studies on arrival were notable for hemoglobin of 8.2 g/dL with no prior baseline available, as well as elevated liver enzymes and alkaline phosphatase. A mononucleosis test was positive.

Results

: Patient underwent angiography, which confirmed a splenic artery pseudoaneurysm. Wire advancement distal to the pseudoaneurysm revealed normal antegrade flow into the spleen without filling of the pseudoaneurysm sac. Inflow and outflow to the pseudoaneurysm was embolized with Azur CX coils (Terumo, Somerset, NJ, USA), and completion angiography demonstrated complete occlusion of the pseudoaneurysm. On postoperative day two, a CTA was obtained which was limited by coil artifact. Mesenteric duplex ultrasound on postoperative day three confirmed a thrombosed splenic artery pseudoaneurysm with no active flow. He recovered without difficulty and was discharged with strict mononucleosis precautions and follow up for his suspected IPMNs.

Conclusion

This patient presented with an asymptomatic giant splenic artery pseudoaneurysm without known etiology. There have been two reports of splenic artery pseudoaneurysms in the setting of a positive Epstein-Barr Virus test; however, there are no documented cases of SAPA along with a positive mononucleosis test and IPMNs. Infectious etiologies should therefore be considered when a finding of SAPA is made. Endovascular treatment should be performed as soon as possible to avoid the 90 % mortality risk associated with rupture. Further studies should be performed regarding correlation between splenic artery pseudoaneurysms, IPMNs, and viral infections.