This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Thyroid Tumor, Subject name: Pathology
[{'content': 'Fine needle aspiration cytology is not enough to diagnose which of the following? \nSelect and explain. \nA. Papillary cancer, B. Follicular cancer, C. Medullary cancer, D. Anaplastic cancer', 'role': 'user'}, {'content': 'Answer: B \nExplanation: - There is no reliable cytologic difference b/w follicular adenomas & minimally invasive follicular carcinomas. - Hence, FNAC is not enough to diagnose follicular cancer of thyroid. - To differentiate b/w these two, extensive histologic sampling of tumor-capsule-thyroid interface to see capsular and/or vascular invasion is needed. - Vascular & capsular invasion is seen in follicular carcinoma which is absent in adenoma - Criterion for vascular invasion is applicable only to capsular vessels & vascular spaces beyond capsule.', 'role': 'assistant'}]