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: Unknown
[{'content': 'Which of the following immunohistochemical marker is positive in neuroendocrine tumor? \nSelect and explain. \nA. Cytokeratin, B. Synaptophysin, C. Calretinin, D. GEAP', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ref. Robbins Pathology. 9th edition. Page. 1099\nThough Cytokeratin is also positive in neruroendocrine carcinoma. For neuroendocrine differentiation more specific marker is synaptophysin and chromogranin\n\xa0\nWHO classification\n\nTypical carcinoids (tcs)\nAtypical carcinoids (acs)\nSmall cell carcinomas (sccs)\nLarge cell necs (LCNECs)\n\n\xa0\nCarcinoid grade I – ruled out because it lacks comedo-like necrosis, has < 0.2 mitotic figures/HP\n\xa0\nAtypical carcinoid:\n\nIncreased mitotic activity -\xa0 per 2-10/10 HPF\nPleomorphism and irregular nuclei with hyperchromatism and prominent nucleoli\nAreas of increased cellularity with loss of the regular, organized architecture observed in typical carcinoid\nAreas of necrosis within the tumor\n\n\xa0\nSmall cell carcinoma – has extensive necrosis (not comedotype as shown in the picture), mitotic figure usually very high (>20/10hpf) and weak staining by neuroendocrine markers\n\xa0\nIHC\xa0 - Neuroendocrine specific – Synaptophysin, chromogranin, CD56', 'role': 'assistant'}]