A 17 cm Hepatic Mass: Multimodality Work-Up of an Indeterminate Liver Lesion

Background. A 76-year-old man with no risk factors for hepatic malignancy was investigated for asymptomatic elevated liver enzymes. A 17 cm hepatic mass was demonstrated on ultrasound, multiphase CT and liver protocol MRI. The final diagnosis was established with a core biopsy of the lesion.

Multimodality work-up. Initial ultrasound evaluation was conducted at a community-based clinic. The ultrasound showed a mildly hyperechoic 12 × 10 cm lesion with non-dilated bile ducts. Multiphase CT showed a giant mass measuring up to 17 cm, replacing most of the right lobe, the caudate lobe, and a portion of the left lobe. The bile ducts were non-dilated and a new left retroperitoneal node was noted. The mass remained indeterminate. MRI with hepatocyte-specific contrast showed a lobulated 17 × 16 × 20 cm lesion, with high signal on T2 and low signal on pre-contrast T1, with diffusion restriction and only faint heterogeneous delayed enhancement. Vessels traversed the mass with mass effect but without narrowing.

Key differentials. Primary hepatic lymphoma was supported by the marked diffusion restriction, minimal enhancement, and vessels traversed rather than obstructed; argued against by its rarity. Intrahepatic cholangiocarcinoma was supported by progressive delayed enhancement, lobulated margins and patient age; argued against by absent capsular retraction, vascular narrowing and hilar obstruction. Infiltrative hepatocellular carcinoma, metastases, epithelioid haemangioendothelioma and abscess were considered less likely.

Final diagnosis. Core biopsy demonstrated diffuse large B-cell lymphoma. Baseline FDG-PET/CT and serial PET/CT and ultrasound documented treatment response.

Teaching points. A very large hepatic mass that displaces vessels without obstructing them, with marked diffusion restriction and very mild enhancement, should raise the diagnosis of lymphoma even when cholangiocarcinoma is the more familiar pathology. Suspecting lymphoma as a potential diagnosis prospectively guided the decision to perform a core needle biopsy in this case.