Ectopic adrenal tissue in the thorax: A case report with in situ hybridization and immunohistochemical studies

Ectopic or accessory adrenal tissues are usually found in the upper abdomen or along the path of descent of the gonads. The occurrence of supradiaphragmatic adrenal tissue is extremely rare. We report a case of ectopic adrenal tissue composed of both cortical and medullary cells in a 99-year-old woman. The lesion was found incidentally in the paratracheal region at autopsy. We performed in situ hybridization and immunohistochemistry to confirm that the ectopic adrenal tissue possessed the same steroidogenesis as a normal adrenal gland. The ectopic adrenal tissue was encapsulated by fibrous tissue and composed of cells expressing all steroidogenic enzyme mRNAs. The centrally located cells showed immunoreactivities for tyrosine hydroxylase (TH), dopamine beta hydroxylase (DBH), and phenylethanolamine-N-methyltransferase (PNMT). Expression of ACTH receptor (ACTHR) was also evident. These findings indicated that this ectopic adrenal tissue had the capability for steroid and catecholamine biosynthesis under the control of ACTH, and that it might function adequately even under a condition of bilateral adrenal insufficiency.