Histological features of mixed neuroendocrine carcinoma and hepatocellular carcinoma in the liver: a case report and literature review.

Primary hepatic neuroendocrine carcinoma (NEC) is rare, and its origin, clinical features, diagnosis and treatment have not been clarified. Primary mixed NEC and hepatocellular carcinoma (HCC) is even rarer and is divided into either combined type or collision type. We report a patient with the combined type of mixed NEC and HCC. A 72-year-old male was diagnosed with HCC and underwent hepatectomy because of the presence of two tumors in his liver. Histological examination demonstrated that one of the tumors had both NEC and HCC components. The transitional zone was noted in the immunohistological examination, and the tumor was determined to be the combined type of primary mixed NEC and HCC. This was the first description of an HCC component being found in an NEC-dominant area in a primary mixed NEC and HCC tumor. Three weeks after hepatectomy, an abdominal computed tomography scan showed extensive regional and para-aortic lymphadenopathy, and early relapse was suspected in the patient. The patient died 3 months after the operation despite treatment with combination chemotherapy. This report describes an unfavorable case and summarizes all the primary mixed NEC and HCC tumor cases that have been previously reported.