18F-FDG-PET/CT Findings of a Primary Hepatic Neuroendocrine Tumor: A Case Report and Literature Review

Primary Hepatic Neuroendocrine Tumors (PHNET) is a rare cancer less than 150 cases have been reported since its initial discovery by Edmondson in 1958. Many of these cases have been described in the literature using features of Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) scans. However, 18F-fluorodeoxyglucose Positron Emission Tomography (18F-FDG-PET/CT) imaging been used less frequently. Only 10% of the hepatic neuroendocrine tumor cases characterized by hypermetabolic lesions were identified using PET imaging. Here, we report a case of PHNET with hypometabolic lesions observed by PET imaging with literature review. A 60-year old man presented with epigastric pain lasting for one month. An abdominal CT examination at a local hospital showed a hypodense lesion with intrahepatic bile duct dilatation in the hepatic caudate lobe, while the chest and pelvic CT were normal. Sonographic imaging showed a solid hypoechoic lesion in the caudate lobe of the liver along with an unclear boundary, a punctate blood flow signal, dilatation of the intrahepatic and extrahepatic bile duct, and right intrahepatic choledocholithiasis. PET/ CT imaging revealed hypometabolism which was due to a lesion in the caudate lobe and hence, primary hepatocellular carcinoma was initially diagnosed. Postoperative histopathology data indicated grade 2 PHNET. After surgery, the patient did not receive any further treatment in the subsequent 6-year follow-up period, during which he was in good health. PHNET is a low-grade malignant tumor for which surgical resection is the major treatment choice. PET/CT imaging plays a key role in evaluating tumor activity and preoperative differential diagnosis of primary and metastatic tumors.