《Slide 91.》Follicular adenoma, Thyroid

A. Brief Descriptions：

1. Derived from follicular epithelium.

2. Not forerunners of cancer except in the exceptional instance.

B. Gross Findings：

1. Well demarcated nodule with a intact fibrous capsule bulging cut surface with a soft, grayish, tan, or brown appearance.

C. Micro Findings：

1. Well-vascularized tumor compression the surrounding gland.

2. Variable secondary degenerative changes: hemorrhage, fibrosis, edema, calcification, bone formation or cystic change. (only edematous and cystic change in our slide).

3. Intact fibrous capsule without capsular or vascular invasion.

4. 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.

5. Tumor cells are polygonal with normochromatic , round to oval nucleoli; well defined cell border with moderate amount acidophilic to amphophilic cytoplasm.

D. Others :

1. Benign encapsulated tumor composed of follicular cells.

E. Reference :

1. Robbins Pathologic Basis of Disease, 6^th ed.  P.1141.

　

 

 

【 Fig. 91-1 (2X)】

　

 

 

【 Fig. 91-2 (4X)】

　

 

 

【 Fig. 91-3 (20X)】