Ectopic Thyroid Tissue in the Adrenal Gland: Report of 2 Cases with Pathogenetic Implications.
Background: Ectopic thyroid tissue is usually found anywhere along the embryonic descent pathway of the medial thyroid anlage from the tongue to the trachea (Wölfler area). However, ectopic thyroid tissue in the adrenal gland (ETTAG) is not easy to understand on the basis of thyroid embryology; because it is so rare, the possibility of metastasis should first be considered. Here, we describe 2 cases of ETTAG with pathogenetic implications and review the literature. Patient findings: Two cases of ETTAG presented as incidental cystic adrenal masses in adult females, one having a congenital hernia of Morgagni. The ETTAG was histologically indistinguishable from normal orthotopic thyroid tissue, and its follicular nature was confirmed by immunohistochemical positivity for thyroglobulin, thyroperoxidase, thyroid transcription factor-1 (TTF-1/Titf-1/Nkx2.1), cytokeratin (CK) AE1/AE3, CK 7, pendrin, human sodium iodide symporter (hNIS), paired box gene 8 (PAX8) and FOXE1 (TTF-2), as well as positivity for the messenger RNA of the thyroglobulin gene by in situ hybridization analysis. No C cells (negativity for calcitonin, cromogranin and synaptophysin) were present. Neither BRAF nor KRAS mutations were detected with real-time polymerase chain reaction analysis. Further work-up did not show evidence of thyroid malignancy. Summary: ETTAG is a rare finding, with only 7 cases reported; women are much more frequently affected than men (8:1) and it usually clinically presents in the fifth decade (mean age: 54, range: 38-67) as a cystic adrenal mass incidentally discovered on abdominal ultrasonography and/or in computed tomography images. ETTAG is composed of normal follicular cells without C cells. The expression of some transcription factors (TTF-1, PAX8 and FOXE1) involved in development and/or migration of the medial thyroid anlage is preserved. Coexistence of a congenital hernia of Morgagni in one patient suggests an over-descent of medial thyroid anlage derived cells in its pathogenesis. Conclusion: Although ETTAG pathogenesis remains unknown, the lack of C cells together with the coexistence of a congenital defect of the anterior diaphragm (hernia of Morgagni) in one of our patients could suggest an over-descent of medial thyroid anlagen derived cells in the origin of this heterotopia.
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GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-N GENE-N GENE-Y CHEMICAL GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-N GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y
FOXE1 thyroglobulin thyroperoxidase thyroid transcription factor-1 TTF-1 Titf-1 Nkx2.1 cytokeratin CK CK 7 sodium iodide pendrin human sodium iodide symporter hNIS paired box gene 8 PAX8 FOXE1 TTF-2 thyroglobulin calcitonin cromogranin synaptophysin BRAF KRAS TTF-1 PAX8