Diagnostic conundrum: massive portal vein pathology in a young patient – benign or malignant?

We present a 23-year-old male referred to a tertiary hospital with 3 weeks of upper abdominal pain, early satiety, and loose stools. There was no history of abdominal surgery, trauma, coagulopathy, or connective tissue disorders. Initial computed tomography (CT) of the abdomen and pelvis demonstrated significant dilation of the portal (9.4 × 5.2 cm) and splenic vein (1.5 cm), with intrinsic homogenous non-arterial enhancing mass (Fig. 1). The differential diagnosis included benign portal vein thrombosis (PVT), or an invasive neoplastic process arising from the liver, pancreas, or bile ducts. Inflammatory markers, liver function, coagulation panels, and tumour markers (AFP, CEA, CA125, CA19.9, and chromogranin A) were unremarkable. A subsequent ultrasound showed absence of flow in bilateral portal veins. Multiphase contrast magnetic resonance imaging (MRI) of the liver and pancreas revealed homogenous non-enhancing T2 hypointense and T1 hyperintense portal vein lesion, with involvement of superior mesenteric veins (Fig. 2). There were no hepatic lesions, splenomegaly, features of portal hypertension, or evidence of tumour thrombus. Subsequent fluorodeoxyglucose positron emission tomography (FDG-PET) did not demonstrate metabolically active disease to indicate malignancy. Due to the unprecedented size of the PVT, a CT guided transhepatic biopsy was performed and did not show typical solid thrombus, mucin, or neoplastic cells. Endoscopic ultrasound (EUS) revealed extensive PVT without doppler flow. There were no lesions in the pancreas, splenic hilum, or duodenum. Further evaluation for underlying connective tissue or genetic disorders was also unremarkable. The patient was treated with therapeutic anticoagulation and symptoms gradually resolved over the following days prior to discharge. Clinical presentation of PVT is variable. Symptoms depend on chronicity and severity of the thrombus.1 Patients can present asymptomatically, with or without features of portal hypertension.1, 2 PVT is a relatively rare phenomenon, with an estimated annual incidence and prevalence rate of 0.7 and 3.7 per 100 000 inhabitants, respectively.3 In comparison, the lifetime cumulative incidence of PVT was 1.0% with equal gender distribution.4 Interestingly, patients with non-malignant and non-cirrhotic PVT are younger at time of diagnosis with a median age of 54 years old.3 In comparison, the median age at diagnosis was 60 years and 67 years in patients with cirrhotic and malignant PVT, respectively.3 Aetiology of portal vein thrombosis (PVT) is diverse, and the majority of patients have more than one precipitating factor.3, 4 Liver disease (40%) and hepatobiliary malignancy (27%) are the two most common risk factors, followed by thrombophilia (22%) and myeloproliferative disorders (11%).2-4 However, it is worth nothing in up to 50% of patients with chronic PVT, the cause remains unclear.2 Management of subtypes of PVT varies significantly. Initiation of Anti-coagulation and management of precipitating factors is the mainstay treatment. Choice of anticoagulation should be individualized based on comorbidities, bleeding risk, and underlying etiology.2, 4, 5 Low molecular weight heparin (LMWH) and unfractionated heparin (UFH) are preferred in the acute setting.6 Recent studies have shown Direct Oral Anti-Coagulants (DOACs) to be safe, cost-effective alternatives, with comparable efficacy and bleeding risk in both non-cirrhotic portal vein thrombosis and venous thromboembolism of atypical locations (VTE-AL).7, 8 European guideline recommendations support minimum treatment duration of 6 months,9 however lifelong anticoagulation may be indicated in the absence of an identifiable systemic cause.2, 5, 6, 9 Knowledge of natural history of untreated non-cirrhotic non-malignant PVT is limited, and spontaneous recanalization without therapy is rare.2, 5 Intestinal ischaemia and infarction are serious complications typically seen in acute PVT with mesenteric vein involvement, which carries significant mortality.1, 10 Whereas chronic PV thrombosis is associated with portal hypertension and development of portal cavernoma and portosystemic shunt.10 Young patients who develop PVT in the absence hepatobiliary risk factors warrant extensive work-up to rule out thrombophilia, myeloproliferative disorders, atypical infections, and most importantly malignancy. High index of clinical suspicion and early intervention is essential to prevent serious complications such as portal hypertension, progressive liver failure, and death. In our case, given stable patient clinical progress and absence of complications, a multi-disciplinary decision was made to prioritize conservative management, as the risk of further invasive diagnostic measures outweighs the benefit. Radiological, endoscopic, and surgical options were limited due to extensive involvement of the intra-hepatic, portal, splenic and mesenteric vessels, and patient may require transplantation for definitive management. Open access publishing facilitated by University of New South Wales, as part of the Wiley - University of New South Wales agreement via the Council of Australian University Librarians. Zhengchao Xu: Data curation; investigation; writing – original draft. Christian Pappas: Data curation; investigation; writing – review and editing. Mina Sarofim: Conceptualization; validation; writing – review and editing. Ruwanthi Wijayawardana: Conceptualization; supervision; validation; writing – review and editing. David Lawson Morris: Conceptualization; supervision; validation; writing – review and editing.