CHANGES IN HORMONE PRODUCTION OF A RECURRENT SILENT CORTICOTROPH ADENOMA OF THE PITUITARY - A HISTOLOGIC, IMMUNOHISTOCHEMICAL, ULTRASTRUCTURAL, AND TISSUE-CULTURE STUDY

A 19-year-old man with blurred vision, headache, and no signs or symptoms of hormone excess was found to have a pituitary adenoma. The tumor was removed by a transfrontal approach. He had postoperative radiation therapy, but subsequently had three recurrences, all removed surgically. By histology, the tumor was a chromophobic, slightly acidophilic piluitary adenoma. Immunohistochemistry revealed the presence of adrenocorticotropin (ACTH) in all four biopsies, α-subunit of glycoprotein hormones, and, to a lesser extent, follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in the third and fourth tumor resection specimens. Ultrastructurally, the tumor had typical features of a silent corticotroph adenoma subtype 2. In tissue culture, the second, third, and fourth specimens released ACTH, α-subunit, FSH, and LH and responded to corticotropin-releasting hormone with increased release of ACTH α-subunit, FSH, and LH. To our knowledge only one silent corticotroph adenoma has been reported previously which expressed plurihormonality. Change in immunohistochemical profile in malignant tumors is a well-known phenomenon; however, it was not reported previously is benign pituitary adenomas. The factors accounting for changing tumor phenotype are unknown. © 1991.