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: Radiology
[{'content': 'Which of the following feature of a thyroid nodule on ultrasonogram is not suggestive of malignancy? \nSelect and explain. \nA. Hyperechogenisity, B. Hypoechogenisity, C. Nonhomogenous, D. Microcalcification', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The hyperechoic structure on ultrasonography suggests a benign lesion. Malignancies always have a hypoechoic or nonhomogeneous hypoechoic structure.\nUSG features of malignancy in a thyroid nodule\n\nHypoechoic / nonhomogeneous / solid \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0\nMicrocalcification \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0\nVariable peripheral rim\nInternal vascularity\nLymph node involvement', 'role': 'assistant'}]