The etiology of intestinal carcinoid tumors is unknown. Carcinoid tumors arise from neuroendocrine cells of gut mucosa, but it uncertain whether differentiated or immature neuroendocrine cells are the origin.
Carcinoids arise from Neuroendocrine cells of endodermal derivation.
The pathogenesis of intestinal carcinoids is unknown. No other sex, racial or geographic preference has been described. These tumors are fairly well circumscribed but not encapsulated, white or pale yellow tan, and very firm due to a marked desmoplastic reaction. The overlying mucosa is usually intact, and the tumor is seen as a submucosal smooth nodule. Large lesions can ulcerate the mucosa or penetrate the serosa.