Thyroid Adenoma

Overview
  • Thyroid adenomas are typically benign neoplasias of the thyroid gland whose cell of origin is the thyroid follicular epithelial cell.
Morphology
  • Gross Appearance
    • Thyroid adenomas usually present as a solitary nodule of the thyroid gland.
  • Histological Appearance:
    • Thyroid adenomas are typically characterized by a uniform arrangement of well-differentiated colloid-containing thyroid follicles. Importantly, adenomas are separated from the surrounding normal tissue by an obvious capsule. Capsular integrity is the most critical factor for distinguishing adenomas from significantly more ominous thyroid carcinomas.
Clinical Consequences
  • Overview
    • Adenomatous thyroid follicles may or may not be functional and thus secrete thyroid hormones. Typically, when adenomas are functional, secretion of thyroid hormones is impervious to normal physiological mechanisms of Thyroid Hormone Regulation. Functional can be distinguished from non-functional adenomas by their capacity to uptake of radioactive Iodine which can be radiographically detected.
  • Non-functional Adenomas
    • Most thyroid adenomas are not functional and thus do not secrete thyroid hormones. Therefore, they solely present as painless nodules of the neck which rarely if large can impinge on local structures and result in dysphagia. The vast majority of non-functional adenomas are benign although a small subset can progress to thyroid carcinoma.
  • Functional Adenomas
    • A small minority thyroid adenomas produce thyroid hormones and typically do so independently of TSH stimulation. Consequently, these nodules may result in the clinical syndrome of hyperthyroidism. Happily, functional adenomas are always benign.