Background: Neuroendocrine tumor (NET) is neoplasm of epithelial cells that differentiates based on neuroendocrine cells. Appendix NET is the third most common gastrointestinal neuroendocrine tumor after the small intestine and rectum one. NET in the appendix is often found incidentally on histopathological examination of appendectomy tissues. Immunohistochemistry of chromogranin A and synaptophysin are the most tumor markers in NET. Objective: To know expression immunohistochemistry chromogranin A and synaptophysin as markers of neuroendocrine tumor (NET) in histopathological preparations of appendicitis. Materials and methods: This is a descriptive study with a cross sectional approach on 52 samples of histopathological appendicitis preparations stained with hematoxylin and eosin (H&E) and immunohistochemistry chromogranin A and synaptophysin as markers of NET Results: NET in the appendix is often found incidentally in histopathological preparations of appendicitis. The suspect of NET in the appendix can be confirmed by immunohistochemical chromogranin A and synaptophysin as markers of neuroendocrine tumors.

neuroendocrine

synaptophysin

chromogranin A

appendicitis

appendix