<prompt> Most common site for carcinoid tumor in the abdomenAppendixLiverIntestinesPancreas  <response>: .CARCINOID TUMOUR It commonly occurs in appendix 65, ileum 25, other pas of GIT and rarely bronchus, testis, ovary. In the small intestine, carcinoids are most often seen within the terminal 2 feet of the ileum. They arise from the enterochromaffin cells Kulchitsky cells found in the crypts of Lieberkuhn. These cells are capable of APUD Amine precursor uptake and Decarboxylation and can secrete vasoactive peptides. Carcinoid syndrome is seen in 40 of patients. Carcinoid in appendix is usually single. But commonly it causes luminal obstruction and so presents with features of appendicitis. Common site is at tipdistal 23. ref:SRB;s manual of surgery ,ed 3,pg no 812 