This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urology, Subject name: Surgery
[{'content': 'A well differentiated follicular carcinoma of thyroid can be best differentiated from a follicular adenoma by \nSelect and explain. \nA. Huhle cell change, B. Lining of tall columnar and cuboidal cells, C. Vascular invasion, D. Nuclear features', 'role': 'user'}, {'content': "Answer: C \nExplanation: A well differentiated follicular carcinoma of thyroid can be best differentiated from a follicular adenoma by capsular invasion/ vascular invasion. This is not made out in FNAC and hence FNAC is not very useful. USG can make out this differentiating feature of follicular carcinoma. Reference : page 482 SRB's manual of surgery 5th edition", 'role': 'assistant'}]