A 65-year-old male was diagnosed with type 0-IIa early gastric cancer of the lesser curvature of the gastric antrum by his previous physician based on an upper gastrointestinal endoscopic examination. The patient was referred to our hospital for treatment, and endoscopic submucosal dissection (ESD) was performed. The histopathological findings showed well-differentiated adenocarcinoma and depth of invasion was limited into the mucosal layer. No vascular invasion or lymphatic invasion was seen, and the resection had been curative. Because there was severe cell atypia and tumor cells with clear cytoplasm were conspicuous, α-fetoprotein (AFP) and glypican-3 staining was performed. The results showed that some of the cells were positive, and we made a diagnosis of AFP-producing gastric cancer. Because AFP-producing gastric cancers are known to be highly malignant, whenever AFP-producing gastric cancer is suspected based on the macroscopic or pathological findings, diagnosis by immunostaining should be proactively taken into consideration.
