Splenic artery pseudoaneurysm

Splenic artery pseudoaneurysms are a rare type of pseudoaneurysmspseudoaneurysm arising from any portion of the splenic artery and its branches. 

Clinical presentation

Unlike splenic artery true aneurysms, splenic artery pseudoaneurysms will nearly always present with symptoms ². Fewer than 200 cases of splenic artery pseudoaneurysms are reported in the English literature ².

Pathology

While they are sometimes grouped under splenic arterial aneurysms, they are distinct entity and are different from true aneurysms of the splenic artery. In contrast to a true aneurysm the pseudoaneurysm wall contains only the intimal and medial layers ². 

Their size can vary and if larger than 5 cm they are called giant splenic artery pseudoaneurysms ³.

Aetiology

They usually occur as a complication of ^1-2:

• pancreatitis
• trauma
• iatrogenic and postoperative causes
• peptic ulcer disease (rarely)

In the case of pancreatitis, the pancreatic enzymes are thought to cause a necrotising arteritis with destruction of vessel wall architecture and fragmentation of elastic tissues.

In the traumatic setting, they are actually more often intra-parenchymalintraparenchymal and rarely involve the propermain splenic artery.

Radiographic features

CT

CT is the modality of choice in assessing splenic trauma:

• true aneurysms will appear just as they do at other locations
• intra-parenchymalintraparenchymal pseudoaneurysms have a similar appearance to active haemorrhage on initial scanning but do not increase in size on delayed phases and follow the blood pool on all phases
• intra-parenchymalintraparenchymal pseudoaneurysms and AV fistulas have a similar appearance and cannot be differentiated on CT
• in contrast, active haemorrhage appears as a high-density density (80-95HU-95 Hounsfield units) material due to the extravasation of IV contrast media that increases in size on delayed imaging

See also

• pseudoaneurysm
• splenic artery aneurysm
• Seurat spleen