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': '40-year old female presented with neck swelling. Gross and histology is shown below.  What is your diagnosis? \nSelect and explain. \nA. Medullary carcinoma thyroid, B. Hashimotos thyroiditis, C. Anaplastic carcinoma, D. Follicular carcinoma', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ref. Robbins Pathology. 9th edition. Page. 1099\nMedullary carcinoma thyroid\nGross\n\nSingle or multiple\nTypically nonencapsulated\nSolid, gray / tan / yellow, firm, may be infiltrative\n\nMicroscopy\n\nRound, polygonal or spindle cells in nests, cords or follicles, defined by sharply outlined fibrous bands\nTumor cells have granular cytoplasm and uniform round / oval nuclei with punctate chromatin\nStroma has amyloid deposits from calcitonin, prominent vascularity with glomeruloid configuration or long cords of vessels, coarse calcifications\n\n\xa0\nIHC – Calcitonin', 'role': 'assistant'}]