<prompt> Most common site for carcinoid tumor is?PituitaryPancreasSmall intestineLungs  <response>: Ans. is c i.e., Small intestine Carcinoid tumors arise from the neuroendocrine cells Argentaffin cells or Kulchitsky cells. The majority are found in GI tract, and more than 40 in small intestine jejunum ileum. The tracheobronchial tree and lungs are the next common sites involved. 