Adult Hepatocellular Carcinoma Coexisting with Extramedullary Hematopoiesis.

Extramedullary hematopoiesis (EMH) in adults usually occurs in the liver, spleen, and lymph nodes when bone marrow hematopoiesis fails. EMH has also been recognized in benign or malignant hepatic tumors, such as hepatoblastoma, hepatocellular adenoma, and vascular tumors. However, it is rarely encountered in hepatocellular carcinoma (HCC) in elderly adults, and the molecular mechanism of EMH in hepatic tumors remains unclear. We present a case of a 74-year-old man without any hematopoietic disorders and hepatitis viral infection who underwent hepatic resection for HCC. Histological examination revealed a well-differentiated HCC with trilineage hematopoiesis in the tumor and non-neoplastic liver. The coexistence of HCC and EMH in adult patients with no hematopoietic disorders is very rare and must be distinguished from poorly differentiated or dedifferentiated HCC and hepatoblastoma.