Chromoendoscopy of an undifferentiated adenocarcinoma. (A) A flat discolored lesion with an unclear border at the lower body of the stomach is shown. (B) Endoscopic view after acetic acid was sprinkled. (C) Endoscopic view after indigo carmine was additionally sprinkled. (D) Endoscopic view after the lesion was washed with clean water. After chromoendoscopy with indigo carmine dye added to acetic acid, the lesion's border was still indistinct and the image was mottled. The lesion was resected by laparoscopic gastrectomy and was shown to be an undifferentiated adenocarcinoma.