Hepatocellular carcinoma presenting as a pancreatic metastasis with no primary liver tumour

A 72-year-old gentleman with no past medical or surgical history presented with haematuria. He underwent investigations for suspected prostate disease. There was no history of cirrhosis, alcohol excess or viral hepatitis. There were no clinical features of endocrine dysfunction, and examination of the abdomen was unremarkable. The full blood count, renal profile and liver function tests were within normal limits. A CT abdomen demonstrated an incidental lesion in the pancreas.

The patient underwent an unenhanced CT kidneys, ureter and bladder (KUB); this demonstrated a soft tissue mass lesion in the tail of the pancreas. Contrast-enhanced studies were performed, which demonstrated heterogeneous arterial enhancement with persistent enhancement in the portal venous phase (Figure 1). The background liver parenchyma was normal, and there were no imaging features of cirrhosis. There was no pancreatic ductal dilatation or lymphadenopathy. This raised the suspicion of a mass lesion.

Contrast-enhanced MRI demonstrated a solitary mass lesion with internal cystic foci and areas of previous haemorrhage on T2 (Figure 2). The enhancement characteristics were consistent with the CT findings. There was no ductal dilatation of the pancreatic or biliary ducts on magnetic resonance cholangiopancreatography.

There was minimal avidity on 68Ga-Dotatate PET/MRI (Figure 3); a neuroendocrine tumour was deemed unlikely.

Hepatocellular carcinoma (HCC) is a primary liver malignancy which results from an accumulation of genetic damage to normal hepatocytes. During hepatocarcionogenesis, malignant cells acquire the ability to invade the portal vein, hepatic vein and lymphatics resulting in haematogenous and lymphatic spread. This is a characteristic feature of advanced, poorly differentiated tumours. Metastatic disease in early HCCs is uncommon [1]. Intrahepatic metastases occur via the spread of tumour cells in the portal venules. The most common sites of extrahepatic disease are the lungs, lymph nodes and bones. Pancreatic metastases from HCC have been described; however, this is extremely rare [2]. To our knowledge this is the first documented case of pancreatic HCC metastases without a primary tumour in the liver visible on relevant imaging.

Pancreatic mass lesions are commonly encountered in clinical practice. They remain asymptomatic until an advanced stage and are usually incidental findings on imaging. Pancreatic adenocarcinomas and neuroendocrine tumours are the most common primary pancreatic neoplasia. Metastases in the pancreas most commonly originate from renal cell carcinoma, melanoma and non-small cell lung cancer [3]. Differentiating pancreatic neoplasia from benign lesions is crucial in ensuring cancer patients receive prompt treatment whilst those with benign disease are not harmed by unnecessary surgical intervention.

Radiological assessment is a crucial step in the characterisation of pancreatic mass lesions. Pancreatic metastases are typically contrast-enhancing lesions which do not cause pancreatic ductal dilatation. A coexisting primary malignancy and calcification within the mass may further support the diagnosis of a secondary lesion. Spectral CT and 68Ga-Dotatate PET/CT and PET/MRI have a key role in differentiating metastases from neuroendocrine tumours by demonstrating avidity following radiotracer injection [4]. In contrast, pancreatic adenocarcinomas typically are non-enhancing mass lesions which compress the pancreatic ducts causing dilatation. Imaging is unable to definitively characterise a pancreatic mass lesion, and biopsies may yield inconclusive results. In selected cases, surgical resection is the only way to obtain a definitive tissue diagnosis.

An endoscopic ultrasound and biopsy of pancreatic lesion were performed, which was inconclusive. The patient underwent a radical left pancreatectomy and splenectomy. The morphological appearances and immunohistochemical profile were consistent with metastatic moderately differentiated hepatocellular carcinoma (Figure 4).

The patient made full recovery postoperatively and is currently discharged and disease-free on 18-month follow-up imaging (Figure 5).

The characterisation of pancreatic lesions often requires a multimodal approach. Imaging is often unable to provide a definitive diagnosis. Pancreatic metastases from HCC are uncommon, and though rare, can occur in the absence of a primary liver lesion.

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