This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
[{'content': 'A 30 yr old man undergoes emergency laparotomy following penetrating injury to abdomen. Coincidentally surgeon notices a 2cm mass at the tip of appendix. It is yellowish brown in colour and firm to touch. IHC is positive for chromogranin  and synaptophysis, negative for ki67. which of the following could be the possible diagnosis ? \nSelect and explain. \nA. Desmoid tumor, B. Lipoma, C. Neuroendocrine tumor, D. Fecolith', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The given case scenario is indicating carcinoid tumor. it is a neuroendocrine tumor.', 'role': 'assistant'}]