Histopathological findings. (a) Visual findings. An uneven tumor could be seen in the submucosa. Lines in the figure show the cross-sections used for specimen preparation. (b) Hematoxylin-eosin staining ×200. Tumor cells exhibit the so-called carcinoid pattern. Cell division was extremely low, at 1/10 hpf, and no vascular invasion or tendency to invade surrounding tissue was seen. (c) Chromogranin A ×100. Tumor cells were strongly positive. (d) Synaptophysin ×100. Tumor cells were strongly positive.
