Association of autonomous thyroid adenoma with chronic thyroiditis.

Coexistence of an autonomous thyroid adenoma (ATA) with chronic thyroiditis suggests a complex pathogeny pointing to the autonomous character of the nodule and to the presence of immunitary disorders. The rarity of this association and the paucity of data prompted us to present 4 cases of a series of 71 thyroidectomized ATA cases. The rarity of ATA associated with chronic thyroiditis, accumulation of radioiodine under the conditions of euthyroidism only at the adenoma level as well as the possibility for the disease to occur in hypopituitarism, all support the hypothesis of an initial thyreotropic deficiency, with subsequent hyperplasia "of necessity". Later on there is an autonomous hyperfunction increasing pituitary depression, with total extinction of the thyroid tissue outside the adenoma. When the two lesions are associated, we consider that initially there was the TSH-dependent thyroiditis that developed during which, by accidental depression of TSH secretion a local hyperplasia occurs which later becomes autonomous.