Fine needle aspiration cytology is not enough to diagnose which of the following?

- 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.