Hepatic neuroendocrine tumors without an identifiable extrahepatic primary

Abstract

Background: Hepatic neuroendocrine tumors without an identifiable primary represent either primary tumors or metastases from occult primaries. Primary hepatic neuroendocrine tumors (NET) are very rare. The natural history of patients with liver only disease is poorly defined. Methods: Patients with resected hepatic neuroendocrine tumors were identified for the years 1998–2017. Clinicopathologic variables were abstracted by chart review and immunohistochemistry reviewed for all specimens. Results: Thirteen patients with hepatic NET, without any evidence of non-hepatic primary disease were identified. Extrahepatic primary disease was not identified during a median follow-up of 38 months (1–164 months). The mean age at diagnosis was 54.7 years, 62% female. Pre-operative evaluation to rule out a primary source included CT enterography (n = 1), EUS/ERCP (n = 8), and octreotide scan (n = 11). Six patients had a solitary lesion, while 7 had multifocal disease. Operations performed were right hepatectomy (n = 4), left hepatectomy (n = 4), central hepatectomy (n = 1) and others had a combination of wedge resections and radiofrequency ablation. Six patients had Grade I disease, 6 were Grade 2 and one patient was classified as Grade 3. Two patients died 20 and 33 months after surgery secondary to disease progression (progressive liver disease and solitary brain metastases), both of which were grade 2 with a Ki-67 of 5-10%. The overall survival was 54.1 months (1–164 months) and recurrence free survival was 25.8 months (1–82 months). Conclusion: Primary hepatic NETs are rare, as are liver metastases without an identifiable primary. The natural history of these tumors is in keeping with other neuroendocrine tumors and is generally favorable, especially for low grade disease.