ABSTRACT
We report herein a case of gastric undifferentiated carcinoma with focal yolk sac tumor and hepatoid carcinoma differentiation. A 57-year-old man was referred after a gastroscopy for anemia evaluation. Gastroscopy revealed an approximately 3 cm ulcerofungating mass occupying the greater curvature of stomach body. Biopsy results revealed a poorly differentiated adenocarcinoma. Left gastric lymph node was enlarged, but there were no evidence of distant metastasis on the abdominal CT. He underwent a radical subtotal gastrectomy and gastroduodenostomy with dissection of the enlarged lymph nodes. Postsurgical histological examination revealed an undifferentiated carcinoma with focal yolk sac tumor and hepatoid carcinoma differentiation. Immunohistochemical staining revealed that the tumor cells were focal positive for AFP, anti-hepatocyte antibody.