A Case of Resected Primary Hepatic Neuroendocrine Tumor

A 70s man presented with a solitary liver tumor measuring 4.5 cm on CT. On contrast-enhanced CT, the tumor appeared partly well-enhanced in the late phase, and the remaining part was enhanced in the early phase and washed out in the late phase. Contrast-enhanced MRIshowed fused multiple nodules, and the enhancement/washout pattern was clearer than that of the contrast-enhanced CT. The tumor showed a defective image in the hepatobiliary phase and a high signal on diffusionweighted imaging. Then, the tumor was diagnosed as hepatocellular carcinoma, and thus, left liver lobectomy was performed. On histological examination of the resected specimen, the tumor was found to be composed of uniform and small tumor cells with solid or trabecular growth fashion. On immunohistochemical staining, synaptophysin and chromogranin A positivity was noted, and the Ki-67 index was 14%. Finally, the tumor was diagnosed as a NET G2. Postoperatively, somatostatin receptor scintigraphy was performed to identify the primary site; however, no obvious primary site could not be identified, and thus a diagnosis of primary hepatic NET was made. Eighteen months postoperatively, the patient is alive without relapse. Preoperative diagnosis of primary hepatic NETs is difficult because NETs present various imaging findings and are rare. Moreover, no accurate preoperative diagnosis was reached in our case, suggesting the difficulty in the preoperative diagnosis of NETs.