《Slide 91.》Follicular adenoma, Thyroid
A. Brief Descriptions：
Derived from follicular epithelium.
Not forerunners of cancer except in the exceptional instance.
B. Gross Findings：
Well demarcated nodule with a intact fibrous capsule bulging cut surface with a soft, grayish, tan, or brown appearance.
C. Micro Findings：
Well-vascularized tumor compression the surrounding gland.
Variable secondary degenerative changes: hemorrhage, fibrosis, edema, calcification, bone formation or cystic change. (only edematous and cystic change in our slide).
Intact fibrous capsule without capsular or vascular invasion.
Growth pattern of tumor:
Solid/trabecular: cellular areas with few or no follicles formed.
Microfollicular: small follicles with minimal amount of colloid.
Normofollicular (simple): the size of the follicles approaches that of non-neoplastic glands.
Macrofollicular (colloid): larger follicles with full colloid.
Tumor cells are polygonal with normochromatic , round to oval nucleoli; well defined cell border with moderate amount acidophilic to amphophilic cytoplasm.
D. Others :
Benign encapsulated tumor composed of follicular cells.
E. Reference :
Robbins Pathologic Basis of Disease, 6th ed. P.1141.
【 Fig. 91-1 (2X)】
【 Fig. 91-2 (4X)】
【 Fig. 91-3 (20X)】