Combined primary hepatic neuroendocrine carcinoma and hepatocellular carcinoma: case report and literature review

BACKGROUND Hepatocellular carcinoma (HCC) can grow in a mosaic pattern, often combined with various non-hepatocellular cells. However, HCC combined with a neuroendocrine carcinoma (NEC) component is rarely reported, and its clinical features, origin, diagnosis, and behavior have not been established. In the literature, mixed HCC-NEC tumors are categorized as either collision type or combined type, depending on their microscopic features. Here, we report a patient with a combined-type HCC-NEC tumor. CASE PRESENTATION An asymptomatic 84-year-old woman was found to have a solid mass in the right lobe of the liver. Laboratory and radiologic examinations showed typical findings of HCC, including arterial-phase enhancement, and portal- and delay-phase washout. She was treated by partial laparoscopic hepatectomy of segment 5. Pathological examination showed that the tumor was predominantly HCC, partly admixed with an NEC component. A transitional zone between the HCC and NEC tissues was also observed. The tumor was finally diagnosed as a combined-type primary mixed NEC-HCC tumor. After the preoperative diagnosis, the patient underwent somatostatin receptor scintigraphy to detect the primary NEC lesion, but no accumulation was found in any other part of her body. She has been free of recurrence for 9 months since the surgery. CONCLUSION Mixed HCC-NEC tumors are extremely rare, and correct diagnosis requires multidisciplinary collaboration. The accumulation of further cases is needed to help understand the exact pathology, diagnosis, and treatment of this disease.