Incidence of ectopic thyroid tissue in the adrenal gland

Abstract

Ectopic thyroid tissue is a rare pathological finding bellow the diaphragm and extremely rare finding is ectopic thyroid tissue in the adrenal gland. Thyroid tissue can be located anywhere along the way of embryological migration pathway of thyroglossal duct. In most cases of ectopic thyroid tissue, it is located in the neck. Pathohistologically ectopic thyroid tissue in all cases was formed of follicular cells that expressed TTF-1, Thyroglobulin, PAX8, and cytokeratin 7, and there was lack expression of calretinin. In the literature we found 15 such cases. Women are much more affected than men (14:1), and it usually presents in the fifth decade (mean age 49). In all cases it was composed of normal follicular cells, and C cells were not found. Review of the literature reveals that adrenal ectopic thyroid tissue is almost always cystic, and has distinctive pathologic features. The most important thing is that ectopic thyroid tissue must be distinguished from metastatic deposits from thyroid gland carcinoma.