Fig. 5

Histopathologic findings. A Low-power magnification of SCC in hematoxylin and eosin staining (HE). SCC, covered with the normal squamous epithelium, is infiltrated diffusely in the tumor (arrows). B High-power magnification of SCC (HE). SCC is moderately differentiated. C Low-power magnification of adenocarcinoma (HE). Scattered adenocarcinoma nests are observed in the tumor. D High-power magnification of adenocarcinoma (HE). Adenocarcinoma is well-differentiated. E AB-PAS staining shows blue adenocarcinoma cells. F Superficial SCC in the squamous epithelium of the lower esophagus. G Distal part of SCC is covered with the normal columnar epithelium (arrowheads). H Several transition parts between SCC and adenocarcinoma components are observed in the primary tumor. The left panel shows SCC (left side on the dashed line) and the right panel shows the adenocarcinoma component (right side on the dashed line). I The SCC component is observed in the No. 11p nodes dissected. J The adenocarcinoma component is observed in the No. 11p nodes synchronously. K No reaction for HER2 is immunohistochemically observed in SCC cells. L A positive reaction for HER2 is observed in adenocarcinoma cells, the staining intensity is judged to be 2+