Fig. 2

Immunohistochemistry staining of the neuroendocrine. A Positive staining for synaptophysin (Syn) (original magnification × 100). B Immunohistochemistry staining for neuroendocrine neoplasm positive for CD56 (original magnification × 100). C Immunohistochemical staining of neuroendocrine neoplasm positive for chromaffin A (CgA) (original magnification × 100). D Immunohistochemistry staining of neuroendocrine neoplasm positive staining for neuron-specific enolase (NSE) (original magnification × 100). E Immunohistochemical staining of neuroendocrine neoplasm negative for CK20 (original magnification × 100). F Immunohistochemical staining for Ki-67-positive cell population in neuroendocrine neoplasm. Ki-67-positive cells accounted for about 1% of the neuroendocrine neoplasm tissue (original magnification × 100)