Giant Extra-Hepatic Thrombosed Portal Vein Aneurysm: Case Report and Review of the Literature

I. Labgaa, Y. Lachenal, P. Allemann, N. Demartines, M. Schäfer

Introduction

Portal vein aneurysm (PVA) is defined as a focal dilatation of the portal venous system, greater than 2cm. PVA is a rare vascular anomaly, observed in 0.43% but its incidence was increasing in recent years with the enlarged use of magnetic resonance (MR) and computed tomography (CT) scans. Most common sites are main portal vein and confluence of splenic and superior mesenteric veins, forming extra-hepatic portal vein aneurysm (EPVA). Although risk factors like portal hypertension and liver cirrhosis have been highlighted, the etiology remains to be clarified. PVA are associated with various complications: thrombosis, aneurismal rupture, vena cava obstruction and duodenum compression. Thrombosis is the most frequent complication with complete thrombosis and non-occlusive thrombus occurring in 13.6% and 6%, respectively. Herein we report the case of a giant EPVA with complete thrombosis, among the largest described so far. A conservative treatment showed satisfying clinical and radiological response. We reviewed the English literature, disclosing 13 cases of thrombosed EPVA4-13.

Case Presentation

A 50-years old woman with no relevant medical history and no underlying liver disease was referred to our Division for acute abdominal pain but no other abdominal or systemic symptom. She did not report weight loss. Palpation of the right upper quadrant showed tenderness but Murphy’s sign was negative. Lab tests showed slightly increased CRP (53mg/L), normal white cell count, undisturbed coagulation blood tests, while liver function remained unremarkable. Tumor markers Ca 19-9 and CEA were also normal, 3 kU/L and 1.1ug/L, respectively. An outside CT showed portal vein aneurysm measuring 88x65mm with complete thrombosis extending to superior mesenteric (SMV) and splenic (SV) veins [Figure 1].

Figure 1: CT-scan showing thrombosed portal vein aneurysm (white arrows) with thrombus extending to SMV (black arrows) and splenic vein (arrowheads).

The risk of rupture being low we decided to treat her conservatively with anticoagulation therapy. We completed our investigations with Eso-gastro-duodenoscopy (EGD) and thrombophilia workup; the former did not show any esophageal varices whereas the latter was unremarkable. The patient was released after two weeks and followed on an outpatient basis. At two months, she reported decreased pain and a control CT demonstrated the decreasing in thrombosis size, measuring 80x55mm, associated with a diminished extension to superior mesenteric (SMV) and splenic (SV) veins [Figure 2].

Figure 2: CT-scan showing decreasing size of thrombus within portal vein aneurysm (white arrows) with diminished extension to SMV (black arrows) and SV(arrowheads).

Discussion

Venous aneurysms remain much less common than arterial ones. The most common location for visceral venous aneurysms is portal system with almost 200 reported cases. Most frequent sites are the main portal vein and the SV-SMV confluence. The mechanisms and etiologies are not well understood but appeared to be acquired or congenital. A significant number of PVA cases did not present any underlying liver disease. Thereby authors supported embryological mechanisms causing PVA. The failure of complete regression of the right vitelline vein may be responsible for a venous saccular enlargement, leading to aneurysm. In our case the patient did not present any risk factor: no underlying liver disease, no history of pancreatitis, trauma or abdominal surgery. These elements support the congenital cause. Therefore a genetic council was achieved and our workup was enlarged. Interestingly, the patient showed anatomical variants: CT revealed four hepatic veins whereas spine X-ray revealed a lumbarization of S1 and a right supernumerary lumbar ribs, lateral to L1. Apparently the patient was an isolated case with negative family history for anatomic anomalies. Although possible, the physiopathological association between her EPVA and these anatomical variants needs to be investigated.

PVA complications are various and thrombosis is the most frequent one. Patients with thrombophilia have a higher risk to develop portal vein thrombosis. In our case this cause was excluded. Our review of the literature disclosed 13 cases of thrombosed EPVA. The largest one, measuring 81x109mm was reported by Oleske A and Hines GL and was also treated conservatively, with success. The level of evidence regarding the management of thrombosed EPVA remains low as only few cases have been published so far.

Nevertheless, authors considered clinically symptomatic patients and complete thrombosis of PVA as indications for surgery. Brock et al. postulated that patients with thrombosis extending to SMV and SV should undergo thrombectomy and restoration of portal vein anatomy; but complication rates of surgical management have not been reported. It can be strongly assumed that a conservative treatment has lower complication rates, and reported conservative treatments of thrombosed EPVA have provided good results, as in our case. Subsequently, we would not consider presence of symptoms or thrombosis as strict indications for surgery, and a conservative approach and follow-up in first intent even for aneurysm of great size or extension to SMV/SV is recommended. This approach is also supported by the low risk of aneurismal rupture, 2.2%. In case of treatment failure, surgical treatment should be considered.

Conclusion

Although rare PVA are being more and more frequent. General surgeons should be made aware of this entity, taking part in a differential diagnosis of abdominal pain. Mechanisms and etiologies remain ill defined. We report the case of the second largest extra-hepatic portal vein aneurysm with complete thrombosis, described so far. The patient was treated conservatively with good clinical and radiological response. This case supports a conservative strategy for PVA, in first intent.

Poster published in

World J Emerg Surg. 2014 Apr 29;9:35. eCollection 2014. Review