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': 'All of the following are helpful for diagnosis of medullary Ca thyroid except - \nSelect and explain. \nA. Spindle cell stroma with few follicles, B. Amyloid deposition, C. Calcitonin in stroma, D. Histological mitochondria is essential for diagnosis', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Important Diagnostic Features of Medullary carcinoma are :\nAcellular amyloid deposition.\nCalcitonin secretion by tumour cells.\nMicroscopically polygonal to spindle cell may form nests, trabeculae and even follicles.\nElectron Microscopy showing variable no. of electron-dense granules (Membrane-bound) within the cytoplasm.', 'role': 'assistant'}]