A: Low power magnification of H&E stain; tumor nest in the wall of the bowel, ribbons and cords of monomorphic cells with salt-pepper chromatin pattern, typically seen in endocrine tumors. B: Neuroendocrine tumor in the wall of bowel and fat (×20 magnification). C: Solid nest of tumor (high power magnification ×40). D: Immunohistochemistry Synaptophysin positive; Synaptophysin stains vesicles in neuroendocrine cells. E: Immunohistochemistry INSMI positive, a specific marker for neuroendocrine. F: Immunohistochemistry AE1/AE3 positive, a neuroendocrine marker.