All of the following are true regarding thyroid adenoma, except:

THYROID FOLLICULAR ADENOMA: Most common benign tumor of thyroid caused d/t G-protein coupled receptor mutation. Typical thyroid adenoma is a solitary, spherical, encapsulated lesion that is demarcated from surrounding thyroid parenchyma by a well-defined, intact capsule. Hence, vascular invasion is not seen in this tumors. Microscopically, constituent cells often form uniform appearing follicles that contain colloid. Follicular growth pattern is usually quite distinct from adjacent non-neoplastic thyroid. Areas of hemorrhage, fibrosis, calcification & cystic change, similar to those encountered in multinodular goiters, are common in follicular adenomas, paicularly in larger lesions.