Well differentiated neuroendocrine tumour of the appendix is an epithelial neoplasm with neuroendocrine differentiation and the most common type of appendiceal tumour. Grossly the tumour appears as a well-demarcated yellow nodule and is frequently localized to the tip of the appendix. Microscopically, the tumour is composed of a uniform population of cells with round nuclei and finely stippled chromatin showing trabecular, acinar, tubular, or nested patterns of growth. By immunohistochemistry, the tumour cells are positive for neuroendocrine markers such as chromogranin, synaptophysin, and S100.