S2595 Solitary Liver Lesions Are Not Always HCC: Metastasis From an Uncommon Site Mimicking a Primary Liver Lesion

Abstract

INTRODUCTION: Non-hepatocellular lesions may be found incidentally during imaging work-up for metastatic disease secondarily involving the liver, with metastatic tumors being the most common malignant neoplasms of the liver. The most common primary site of these metastasis is colorectal cancer, followed by breast, lung, and pancreas. Clinical history can be vital in the work-up of primary versus metastatic malignancy in tumors with less common sites of origin, especially when only a solitary liver lesion is identified and initially more suggestive of a primary liver lesion. CASE DESCRIPTION/METHODS: Seventy-two-year-old man who presented to the liver clinic for evaluation of a liver lesion seen on whole body scan (PET). Patient did not have prior history of liver disease or cirrhosis. He denied smoking, drinking alcohol or illicit drug use. He had no chronic or active hepatitis with good synthetic liver function (INR 1.1 sec, bilirubin 0.4 mg/ dL, albumin 4.2 g/dL, creatinine of 1.04 mg/ dL and alpha fetoprotein was less than 2 ng/ml). Past history significant for nasopharyngeal squamous carcinoma 3 years ago treated with chemoradiation. His last colonoscopy was unremarkable. PET scan showed interval appearance of the tracer avid low-attenuation lesion in the left lobe of the liver, segment 4A, concerning for primary neoplasm. He underwent a liver biopsy which showed poorly differentiated malignant cells. The malignant cells were positive for squamous markers p63 and CK5/6 on immunohistochemical stain (Image 1-2). In situ hybridization for EBV was also positive, consistent with metastatic non-keratinizing nasopharyngeal carcinoma. Patient was referred to oncology for further management. DISCUSSION: Liver metastases from head and neck cancer are rare (4.4%) and has a median survival of 4 months. When present in the liver, metastatic EBV-associated non-keratinizing nasopharyngeal carcinoma can histologically mimic hepatocellular carcinoma, neuroendocrine tumors, and small cell carcinoma. In the context of a solitary hepatic lesion on imaging, exclusion of hepatocellular carcinoma requires correlation with the patient's prior history and immunohistochemical staining on biopsy tissue. In this case, the known history of nasopharyngeal carcinoma helped to exclude the rare possibility of a primary squamous cell carcinoma of the liver, which has been proposed to arise following chronic irritation in patients with biliary cysts or stones, with resultant squamous metaplasia and malignant transformation.Image 1.: Liver biopsy showing positive immunohistochemical marker: Cytokeratin 5/6.Image 2.: Liver biopsy showing positive immunohistochemical marker: P53.