A Case of Primary Hepatic Neuroendocrine Tumor with Suspected Bile Duct Invasion and Difficulty in Preoperative Diagnosis

Abstract

Primary hepatic neuroendocrine tumors (PH-NETs) are rare, and preoperative diagnosis is often difficult. A 58-year-old woman was referred with a gourd-type tumor in liver S1/S4 on computed tomography (CT). The tumor had increased in size over the previous 6 years. CT showed a 7-cm-diameter tumor with a clear boundary in liver S1/S4, and the hepatic duct of the right posterior segment was slightly dilated. The patient was diagnosed with a primary malignant tumor of the liver with bile duct invasion and underwent left hepatectomy with extrahepatic bile duct resection. Tumor pathology showed cells with homogeneous nucleation with cord-alveolar structure and eosinophilic stroma. Immunostaining was negative for hepatocytes and positive for CD56 and synaptophysin. With a Ki67 index (MIB-1 index) of 5% and a cell division pattern of 3/10 on high-power field examination, the tumor was classified as NET-G2 based on the 2010 WHO classification. No primary lesions were found in any other organs, so the patient was diagnosed with a PH-NET. There has been no recurrence as of 41 weeks after surgery.