Gastric yolk sac tumor complicated with beta-human chorionic gonadotropin-producing metastases

This report describes the case of 74-year-old man who had a gastric yolk sac tumor complicated with beta human chorionic gonadotropin (beta hCG) producing metastases. He was a heavy drinker. He was admitted to the hospital for abdominal pain and fullness. Based on computed tomography and gastric endoscopy he was diagnosed to have gastric cancer that had metastasized to the liver, lung and lymph nodes. The level of serum alpha fetoprotein (AFP) was high at 523 ng/mL. He died of multiorgan failure six days after admission. The autopsy revealed the stomach tumor to be an AFP-positive yolk sac tumor. Lymph node metastases showed the same characteristics as the stomach tumor. However, the lesions on the liver and lung were negative for AFP and positive for hCG. The yolk sac tumor seemed to have retrodifferentiated to form an hCG-producing tumor in the metastatic lesions. A gastric yolk sac tumor is extremely rare and only eight cases of gastric yolk sac tumors have been previously reported in the literature. To avoid a misdiagnosis, careful attention should be paid to the above-mentioned morphological features and immunohistochemical findings, in addition to the clinical findings.