What is the best course of action for a patient with a painless paraumbilical mass, obstructive jaundice, and a dual energy CT scan of the abdomen showing a lesser sac mass and hyperdense masses in the liver?

Immediate Management: MRI with Liver-Specific Contrast and Multidisciplinary Oncology Consultation

This patient requires urgent MRI with MRCP and liver-specific contrast (gadoxetate disodium) to characterize the lesser sac mass and hepatic lesions, followed by immediate multidisciplinary oncology consultation for suspected advanced pancreaticobiliary malignancy with portal vein thrombosis and liver metastases. 1, 2

Critical Imaging Next Steps

MRI with MRCP is the superior modality for evaluating this complex presentation and should be obtained urgently for the following reasons:

• MRI with gadoxetate disodium is more sensitive than CT for detecting liver metastases from pancreaticobiliary malignancies, which is the primary concern given the hyperdense left lobe masses 1
• MRI has comparable and slightly better accuracy than CT (90.7% vs 85.1%) for diagnosis, local staging, and surgical planning of pancreaticobiliary malignancies presenting with biliary obstruction 1
• MRCP provides superior visualization of the biliary tree and can better delineate the relationship between the lesser sac mass, the pancreatic body, and the caudate lobe 1, 2
• The patient already has contrast-enhanced CT, so MRI adds complementary information without redundancy 1

Diagnostic Considerations Based on CT Findings

The imaging findings suggest advanced malignancy with several concerning features:

• The 10.95 cm lesser sac mass with continuity to both the pancreatic body and caudate lobe represents either primary pancreatic malignancy with hepatic invasion or primary hepatic malignancy 1
• Portal vein thrombosis (2.19 cm filling defect) in the setting of a pancreaticobiliary mass strongly suggests malignant invasion, which significantly impacts resectability 1
• Multiple hyperdense enhancing masses in the left hepatic lobe are highly suspicious for metastatic disease, particularly given their heterogeneous enhancement pattern 1
• Dilated intrahepatic ducts without extrahepatic ductal dilatation suggests portal biliopathy from portal vein thrombosis or hilar obstruction from the hepatic masses 1, 2

Tissue Diagnosis Strategy

After MRI characterization, tissue diagnosis is essential before initiating treatment:

• EUS with fine-needle aspiration (FNA) has sensitivity of 90.8% and specificity of 96.5% for pancreatic or periampullary masses and should be considered if the mass is accessible 2
• Image-guided biopsy of the hepatic lesions may be technically easier and provide definitive diagnosis of metastatic disease 1
• ERCP may be needed for biliary decompression if jaundice worsens, but therapeutic intervention should follow tissue diagnosis when possible 1, 2

Addressing Portal Biliopathy

The dilated intrahepatic ducts with portal vein thrombosis represent portal biliopathy:

• This occurs from venous collaterals compressing the bile ducts in the setting of portal vein thrombosis 1
• MRCP is superior to CT for evaluating hilar biliary obstructions and will better define the biliary anatomy 1
• Biliary decompression may be needed if bilirubin continues rising, but the underlying malignancy must be addressed 2

Critical Pitfalls to Avoid

Do not proceed directly to ERCP without tissue diagnosis, as this patient likely has unresectable disease based on:

• Portal vein thrombosis suggesting vascular invasion 1
• Multiple liver lesions concerning for metastases 1
• Large tumor size (>10 cm) 1

Do not assume this is cholangiocarcinoma or GIST without tissue confirmation, as the CT findings could represent:

• Hepatocellular carcinoma with bile duct tumor thrombus (though less likely given the mass configuration) 3
• Pancreatic adenocarcinoma with hepatic metastases (most likely) 1
• Other rare pancreatic malignancies 4

Do not delay oncology consultation, as this patient will likely need:

• Palliative chemotherapy rather than surgical resection 1
• Biliary stenting for symptom management 2
• Multidisciplinary tumor board discussion 1

Prognostic Considerations

This presentation suggests advanced disease with poor prognosis:

• Portal vein involvement and liver metastases typically preclude curative resection 1
• Obstructive jaundice as the presenting feature in pancreaticobiliary malignancy often indicates advanced stage 3, 5
• The patient's polycystic kidney disease and renal function should be considered when planning contrast studies and chemotherapy 6