Giant Pseudoaneurysm of the Splenic Artery: Size/Rupture Correlation.

Abstract

True arterial aneurysm is defined as a vascular lesion that involves the three layers of the arterial wall causing a vascular bulge. On the other hand, a false aneurysm, also known as pseudoaneurysm (PSA), is a vascular lesion that develops usually following a tear in one or two of the three arterial wall layers, with the developing lesion being contained by the outer adventitia or the local hematoma surrounding the PSA [1]. Giant PSA is defined as a vascular lesion greater than 5 cm in diameter. The splenic artery is the most common visceral artery to be involved in true and false aneurysms, with rates of 60% and 40%, respectively [2]. Although the prevalence rate of splenic artery aneurysm is reported to be 0.2-10.4%, the exact prevalence rate is yet to be known [3]. Splenic artery PSA is even rarer, with merely 300 cases reported in the English literature. Recently, due to the considerable increase in the use of the various imaging tests, such as abdominal ultrasound (US), computed tomography (CT) scan and magnetic resonance imaging (MRI), splenic artery aneurysms and PSA are detected with an increasing frequency [2]. Unlike true aneurysm, which is usually asymptomatic and incidentally discovered, splenic artery PSAs are usually symptomatic [2]. The most commonly reported symptoms are abdominal pain and hemorrhage, either intra-abdominal (into the peritoneal cavity) or intra-luminal (into the gastrointestinal (GI) tract) [4]. In a case series article, only 2.5% of splenic artery PSAs were incidentally found [2]. Etiologies for splenic artery PSA are diverse and include mainly pancreas-related pathologies (52%) (e.g., chronic pancreatitis the most common, acute pancreatitis and pancreatic pseudocyst), post thoraco-abdominal trauma (29%), post-surgical complication (3%) and peptic ulcer disease (2%) [2, 5]. The mechanism behind splenic artery PSA due to pancreasrelated pathology is explained by the “autodigestion theory”: leakage of pancreatic fluid, which includes proteolytic enzymes, into the nearby structures, resulting in structural damage of the arterial wall with subsequent PSA formation [6]. Although any artery can be affected, the most common is the splenic artery, followed by the gastroduodenal artery (GDA). The major concern regarding true or false splenic artery aneurysm is rupture, which may be lethal if left untreated [2]. Mortality rates following untreated ruptures are reported to be as high as 90% [7]. Splenic artery PSAs possess a greater risk for rupture than true aneurysms, and thus, immediate management is almost always required for the treatment of PSAs regardless of size [5, 7]. The risk of rupture with consequent hemorrhage is high at about 37% for splenic artery PSA [7, 8]. For true splenic artery aneurysm, a strong relationship exists between the size of the aneurysm and the risk for rupture and bleeding. On the contrary, it has been claimed that this relationship does not exist for the PSA subgroup [9], and size is not included as a risk factor for rupture. The previously mentioned say is relatively an old one, which lacks scientific based studies and has never been statistically proven. Due to the lack of reported studies about the aforementioned size/rupture risk correlation of splenic artery PSA, and following the hypothesis that larger PSAs have a greater potential for rupture, the aim of this article is to review the pertinent and available articles (mainly case reports and case series) in the English literature concerning splenic artery PSA, specifically the giant type, to find out if this subgroup of splenic artery PSAs have a higher risk for rupture and bleeding (due to larger diameter). A search in PubMed was conducted, based on the “PICOS” acronym. Headings and text words were used to identify studies (mainly case series and case reports) published regarding giant splenic artery PSA. The following search terms were included: “splenic artery pseudoaneurysm”, “pseudoaneurysm of the splenic artery”, “giant pseudoaneurysm of the splenic artery”, “giant splenic artery pseudoaneurysm”, and “giant visceral artery pseudoaneurysm”. All reported cases of giant splenic artery PSA were included, and data regarding patients’ demographics, etiology, clinical presentation, diagnostic technique and therapeutic option were collected. Reviewing the current English literature revealed almost 300 cases of splenic artery PSA, 40 of which (13.3%) are of the giant type. Of the 40 patients, 25 were males and 15 were females (male/female ratio of 1.6:1). The average age at diagnosis was 48 years old (age range 8 78 years old). The most common precipitating etiological factor was chronic pancreaManuscript submitted December 1, 2022, accepted January 6, 2022 Published online February 28, 2023