LAUSR

A 78-year-old woman is presented to our hospital with a hepatic mass on routine physical examination. She was almost asymptomatic. Physical examination was unremarkable. There was no meaningful finding in the laboratory examination. Abdominal unenhanced and contrast-enhanced computed tomography (CT) scan showed a 5.3 × 6.2 cm solid mass in the left lobe of the liver (Fig. 1). Due to the similar appearance, hepatocellular carcinoma, intrahepatic cholangiocarcinoma, or echinococcal cysts was considered for preoperative diagnosis. The patient eventually underwent a liver resection of the left lateral lobe. Pathological examination revealed well-differentiated, grade 2 neuroendocrine tumor (Fig.2a). Immunohistochemical analysis indicated tumor cells positive for Synaptophysin (Fig. 2b), CD56 (Fig.2c), and Ki-67 index≤10% (Fig. 2d) and negative for chromogranin A, PCK, CK7, CK20, GPC-3, and MUC-1. Moreover, no other primary sites have been identified, supporting the diagnosis of primary hepatic neuroendocrine tumor (PHNET). Postoperative recovery of the patient was well. Neuroendocrine tumor (NET) arises from the neuroectodermal cells that are dispersed throughout the body. The incidence rate of NET is 6.25 /100,000 individuals per year in the USA. PHNET is a rare neoplasm due to the neuroectodermal cells that do not routinely migrate to the liver, accounting for about 0.4% of all NETs. The etiology and pathogenesis of PHNET are not completely clear. Most patients have nonspecific clinical presentation such as asymptomatic or upper abdominal pain. Only 6.8% of PHNET patients present with the classic carcinoid syndrome that includes abdominal pain, diarrhea, and skin flushing. There is no known unique diagnostic clinical, laboratory, or radiological features. Thus, the diagnosis of PHNET is still difficult till now. The diagnosis of PHNET requires a continuum starting from preoperative to postoperative processes. If PHNET diagnosis is considered, primary lesions in other organs should be excluded first. In addition, long-term follow-up is required to search for extra-hepatic primary. Percutaneous needle liver biopsy may be able to improve the chance of preoperative diagnosis. Management of PHNET remains controversial, including surgery, transarterial chemoembolization, radiofrequency ablation, liver transplantation, and chemotherapy. Most authors suggest surgery with complete resection and negative margins should be the preferred treatment. A study showed the 5-year survival rate ranges from 74%–78% after hepatectomy, however, the recurrence rate remains as high as approximately 18% 1 . Ki-67 index is an important risk factor for tumor recurrence. Hwang et al. found that the average Ki-67 index of patients without recurrent disease after surgery was 1.7% 2 . Meanwhile, it is worth noting that postoperative PHNET recurrence may not be immediate after surgery, and it has been reported that there is a lesion recurrence in 13 years after operation 3 . Therefore, long-term postoperative followup is very important. Further studies should focus on how to identify diagnosis and on effective treatment options.