A CASE OF PITUITARY SOMATOTROPH ADENOMA WITH CONCOMITANT SECRETION OFGROWTH-HORMONE, PROLACTIN, AND ADRENOCORTICOTROPIC HORMONE - AN ADENOMA DERIVED FROM PRIMORDIAL STEM-CELL, STUDIED BY IMMUNOHISTOCHEMISTRY,IN-SITU HYBRIDIZATION, AND CELL-CULTURE

Somatotroph adenomas often secrete prolactin (PRL) besides growth horm one (GH) and are sometimes immunostained for other anterior pituitary hormones or their subunits, such as thyroid-stimulating hormone (TSH) beta-subunit and glycoprotein hormone alpha-subunit (alpha SU). Howeve r, somatotroph adenomas showing hypersecretion of adrenocorticotropic hormone (ACTH) are extremely rare. There have been, to our knowledge, only five published reports on somatotroph adenomas accompanied by exc essive ACTH secretion. Here we report a case or intracavernously invad ing somatotroph macro-adenoma with high serum GH, PRL, and ACTH levels . We examined the case using immunohistochemistry (IHC), in situ hybri dization (ISH), and cell culture, and confirmed GH, PRL, and ACTH, as well as alpha SU, production, and the expression of Pit-1 protein by t he adenoma, which is known as a transcriptional Factor for GH, PRL, an d TSH, not for ACTH. Therefore, the presence of unknown transcriptiona l factor other than Pit-1, common to GH, PRL, and ACTH, may be specula ted to be expressed in this adenoma. In our previous study, we had fou nd plurihormonal mRNA expression, especially for ACTH, the beta-subuni t of follicle-stimulating hormone and luteinizing hormone in some soma totroph adenomas, using non-radio-isotopic ISH, and suggested that the se adenomas might be derived from plurihormonal primordial stem cells. Our present case is significant from the viewpoint of histogenesis of pituitary adenomas, because it further supports the cell origin of so matotroph adenomas from plurihormonal primordial stem cells, and moreo ver it suggests the presence of unknown transcriptional factor other t han Pit-1, common to GH, PRL, and ACTH.