Gastric adenocarcinoma with choriocarcinomatous and hepatoid differentiation

We report a patient with gastric adenocarcinoma with choriocarcinomatous and hepatoid differentiation. A 67-year-old man visited our hospital for further evaluations due to gastric adenocarcinoma. The gastric cancer was located in the prepyloric area and appeared to be a protruding mass with an infiltrative growth pattern. Initial pancreatic and postoperative hepatic and pulmonary metastases were detected radiologically. Microscopically, choriocarcinomatous and hepatoid differentiation was observed with a moderately differentiated adenocarcinoma. The choriocarcinomatous components were positive for β-hCG and the hepatoid components were positive for α-fetoprotein (AFP). These uncommon pathological patterns are supposed to arise from the retrodifferentiation pathway of primary gastric adenocarcinoma. The preoperative laboratory data revealed elevated serum AFP (773.4 ng/mL) and carcinoembryonic antigen (62.2 ng/mL), whereas other tests were unremarkable. The prognosis of gastric adenocarcinoma with choriocarcinomatous and hepatoid differentiation is very poor; our patient died 4 months after the operation.