This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Surgery
[{'content': 'Malignant cold nodule in thyroid diagnostic on USG by all EXCEPT \nSelect and explain. \nA. No cystic lesion, B. Irregular margins, C. Calcification at margin of tumour, D. Hypoechoic', 'role': 'user'}, {'content': 'Answer: A \nExplanation: (A) No cystic lesion > USG can also be used to aid in the differentiation between benign and malignant nodules. The following criteria can be used by USG, and favor a diagnosis of malignancy:1) Absence of a halo sign2) Uniformly solid tumor with occasional central necrosis3) Irregular margins4) Fine calcifications5) Heterogenous echos and large size6) Surrounding tissue invasion', 'role': 'assistant'}]