Fig. 2

Determination of vascular invasion by elastin staining + CK (AE1/AE3) immunohistochemistry (E&IHC) and determination of the intratumoral region and peritumoral region. A Vascular invasion is indefinite (HE). The red arrow shows carcinoma nest adjacent to the artery, suggestive of vascular invasion. B Vascular invasion (E&IHC). The blue arrow shows the elastic fiber (purple color) clearly outlining the structure of the blood vessel with carcinoma nest (brown color) invasion. C Vascular invasion is indefinite (HE). The red arrow shows a space between the carcinoma nest and the surrounding fibrous stroma, suspected to be caused by cancer nest contraction. D Vascular invasion (E&IHC). The blue arrow shows the elastic fiber (purple color) clearly outlining the structure of the blood vessel with carcinoma nest (brown color) invasion, which is identified as vascular invasion. E Determination of the intratumoral region and peritumoral region (HE). The peritumoral region included the junction between the tumor and normal tissue and the normal tissue area outside the tumor (including the region at the dotted line and the region from the dotted line to the esophageal fibrous membrane). The images of (A), (B), (C), and (D) are magnified 200 × , and (E) is 25 ×