Multiple liver metastases of a neuroendocrine carcinoma of unknown origin

Neuroendocrine tumor (NET) usually occurs in the gastrointestinal system, pancreas, tracheobronchial tree and lung. We report a NET case of unknown origin, which was diagnosed after liver resection. A 67-year-old man was given a diagnosis of liver tumor and lymph node metastasis in the hepatoduodenal ligament. The liver tumor was 20 mm in diameter and was located at segment 6. FDG-PET/CT showed high-level FDG accumulation in the tumor and the lymph node. He underwent liver resection of segment 6 and lymphadenectomy. Pathological diagnosis was neuroendocrine carcinoma (NEC). In addition, multiple liver metastases were found in the resected liver. Therefore our clinical diagnosis was multiple metastasis of NEC with unknown origin. Since multiple liver metastases were found 7 months later, the patient was treated by chemotherapy, octreotide administration, radiofrequency ablation and transarterial chemoembolization. He died 34 months after the operation. NET often spreads to the liver when it is detected, but operation is recommended if they are resectable. Although the prognosis of NEC is bad, long-term survival can be achieved by multidisciplinary strategy in some cases.