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| Adenoma |
| Etiology |
•The etiology of throid adenoma is unknown. |
| Pathogenesis |
•The adenoma represents a initial response to TSH but
often either become or are to begin with autonomous.
•Initially, the amount of thyroid hormone secreted by
the adenoma may be insufficient to cause metabolic
disturbance.
•However, as the adenoma grows larger and if it remains
functional, the patient may exhibit signs of
hyperthyroidism.
•In such cases, do to feedback inhibition of TSH synthesis, the remainder of the thyroid may become atrophic. |
| Epidemiology |
•Thyroid adenomas are not uncommon, solitary nodules in the thyroid.
•They can occur at any age.
•Females out number males by a ratio of 3 or 4 as to 1. |
| Clinical |
•The patients usually present with a history of a
single nodule that has been growing over months or
years.
•The patient may exhibit signs of thyrotoxicosis. |
| General Gross Description |
•Grossly, the tumor may be 1 to 10 centimeters in size.
•It is soft and fleshy and may have cystic areas.
•It is almost always encapsulated and solitary. |
| General Micro Description |
• Microscopically several varieties have been described.
•These include the trabecular, fetal, colloid and
H•rthle cell.
•The trabecular adenoma is composed of sheath cords of
small cells.
•The fetal adenoma is composed of small follicles,
devoid of colloid and embedded in a blue staining,
loose matrix.
•The colloid adenoma resembles normal thyroid and is
composed of normal looking acini filled with colloid.
•The H•rthle cell adenoma is composed of acini that are
lined by large cells with central nuclei and prominent
granular, deeply acidophilic cytoplasm.
•The capsule of the adenoma is intact and is composed
of fibrous tissue and compressed normal thyroid.
•For an adenoma to be a true adenoma and not a follicular carcinoma, there must be no invasion of the capsule by the tumor. |
| Reference |
• Cotran RS, Kumar V, Robbins SL: Robbins Pathologic Basis of Disease. 5th ed. Philadelphia, W.B. Saunders, 1994, pp. 1134
• Harrison^s Principles of Internal Medicine, 13th Ed: Isselbach et. al. (eds). New York, McGraw-Hill, 1994, pp. 1948
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