Teaching Case

A two day history of band-like constant upper abdominal pain which started in the right hypochondrium. No relationship with food intake, no vomiting, no diarrhoea, no fever. Clinical examination showed an obese patient with mild pain upon palpation of the right upper quadrant. No guarding or other signs of peritonitis.

Abdominal ultrasound was performed on the emergency ward. A sharply defined hypo-echoic mass was seen (5.2cm) in the epigastric region. It was hard to define the mass as intrapancreatic or peripancreatic. There was no pancreatic atrophy nor dilatation of the Wirsung duct. There was no detectable flow in the splenomesenteric venous confluence nor in the main portal vein. No dilatation of the biliairy system and no ascites where seen. The liver showed a coarse and heterogeneous echo-texture.
Triple-phase MDCT was performed. The splenomesenteric venous confluence was enlarged (5.4cm) and spontaneously hyper-dense (65HU). There was mass effect with anterior displacement of the pancreatic head. Slight infiltration of the peripancreatic fat planes was observed. The portal venous phase showed no enhancement of the spleno-mesenteric confluence and the thrombus extended in splenic vein, upper mesenteric vein, main portal trunk and intrahepatic portal veins. Mild splenomegaly, with no other signs of portal hypertension.

A. Aneurysms of the portal venous system (PVA) are extremely rare and represent only 3% of all venous aneurysms [1]. It was first described by Barzilai and Kleckner in 1956. Until 2014 less than 200 cases have been reported [2]. PVA is defined as a portal vein diameter exceeding 1.9 cm in cirrhotic patients and 1.5 cm in normal livers [3]. It can be congenital or acquired (in which the main cause is portal hypertension in liver cirrhosis) [1, 2, 4, 5]. Aneurysm localisation include main portal trunk (38.4%), spleno-mesenteric confluence (23.6%) and portal bifurcation/intra-hepatic (38%) [2].
B. Patients are often asymptomatic or can present with unspecific upper abdominal pain [2, 4]. Clinical features and laboratory findings can be variable depending on the presence of underlying liver pathology or portal hypertension.
C. Doppler ultrasound is often used as the first imaging technique in unspecific upper abdominal pain. It depicts the aneurysm as an anechoic mass showing direct luminal continuity with the portal venous system and can evaluate the blood flow, in some cases further workup may not be necessary [2, 4, 6, 7]. A thrombosed aneurysm can be harder to identify because they are hypo-echoic rather than anechoic and there is no blood flow present, if so the differential diagnosis with malignant or benign cystic pancreatic lesions complicated with vein thrombosis can be difficult. A CT examination can demystify diagnostic problems and helps determine the accurate location of the aneurysm, its dimensions and relations with adjacent organs [2, 6, 7].
D. Conservative management with regular follow-up is the best option for the majority of patients (especially in small, asymptomatic aneurysms in the absence of cirrhosis or portal hypertension)[8]. Most of the portal venous system aneurysms are stable and have low risk of complications[9]. Thrombotic risk factors are similar to non-aneurysmal PV thrombosis. If thrombosis is present anticoagulation therapy is recommended resulting in complete or partial recanalisation in up to 80% of patients [8]. Surgical management of thrombus or aneurysm is controversial. The management of PVA should be on a case-by-case basis, depending on symptoms, presence of cirrhosis and PVA size.
E. PVA is a rare condition, unknown to many radiologists and clinicians. Clinical presentation is unspecific but ultrasound and CT are excellent diagnostic tools. Underlying liver disease and aneurysm complications need to be identified. Management is not standardised, mainly due to the fact that the majority of literature consists of isolated case reports [2].