<prompt> Which of the following is true about gastrointestinal carcinoid tumor?Alcohol has no effect on the flushing attacksOccur most commonly in jejunumTumors most commonly produce histaminePreoperative octreotide scanning can detect extent of the disease  <response>: Answer- D. Preoperative octreotide scanning can detect extent of the diseaseThese neuroendocrine tumours occur throughout the gastrointestinal tract, most commonly in the appendix, ileum and rectum in decreasing order of frequency. Appendicular carcinoid tumours are most commonly noted as an incidental finding at appendicectomy.Carcinoid tumours arise from Kulchitsky cells at the base of intestinal crypts of LieberkuhnThe tumours can produce a number of vasoactive peptides, most commonly S-hydroxytryptamine serotonin, but also histamine, prostaglandins and kallikrein.Classically, the flushing attack are induced by alcohol.The extent of disease can be assessed preoperatively using octreotide scanning, which may detect otheise clinically apparent primary and secondary tumour. 