Figure 3

Histopathologic findings. (a) A low-power view of the line (from A to B) shown in Figure 2. The neuroendocrine carcinoma (NEC) and adenocarcinoma components of the tumor were adjacent and partially intermingled. The NEC component had invaded the submucosa with vascular permeation (arrow). (b) The NEC component showed a positive response for CD56 staining (immunohistochemical stain). (c) A magnified view of the squared area at the left in (a). The NEC component showed a solid and trabecular pattern, and the tumor cells had elongated hyperchromatic nuclei and scant cytoplasm (hematoxylin and eosin stain (H&E); original magnification, ×117). (d) A magnified view of the squared area in the middle in (a). A borderline area of NEC and well-differentiated adenocarcinoma showed a histological transition (H&E; original magnification, ×117). (e) A magnified view of the squared area at the right in (a) showing well-differentiated tubular adenocarcinoma confined to the mucosa and submucosa (H&E; original magnification, ×117).