alpha-Fetoprotein producing gastric carcinomas: a comparative study of three different subtypes.

Nine cases of gastric carcinoma with excessive production of α‐fetoprotein (AFP) were analyzed morphologically, histochemically and biochemically. Consequently, it was proposed that AFP‐producing gastric carcinomas should be divided into three subtypes: (i) hepatoid type; (ii) yolk sac tumor‐like type; and (iii) fetal gastrointestinal type. The data from the study suggested that the hepatoid type and the yolk sac tumor‐like type are derived from liver cell metaplasia and yolk sac cell metaplasia of common poorly differentiated medullary adenocarcinoma, respectively. The fetal gastrointestinal type seemed to be a result of the imitation of fetal gastrointestinal epithelium by common tubular adenocarcinoma. The hepatoid type was also the most common in the file of AFP‐producing gastric carcinoma. Unfortunately, most of the hepatoid types seemed to be highly malignant.