Aim: To disclose the nature of plurihormonality and pluripotentiality of growth hormone (GH)-secreting adenomas.
Methods: A total of 242 patients with GH-secreting adenomas were studied by immunohistochemistry, electron microscopy and clonal analysis (X-linked human androgen receptor gene assay).
Results: GH-secreting adenoma showed a greater variety and number of hormones produced compared with those of PRL-secreting adenomas (p<0.01, Welch’s t-test). The number of cases with GH-secreting adenoma that simultaneously produced ACTH were 50 (21%) out of 242. There were two different types of co-localization of ACTH- and GH-secreting cells within adenoma; (1) adenoma with co-localized ACTH- and GH-immunoreactive cells in a random pattern, and (2) adenoma with a small cell cluster of ACTH-immunoreactive cells within GH-secreting adenomas. There were three different tissue phenotypes in GH-secreting adenomas; (a) mixed tumors composed of adenoma and neuronal cells, (b) co-localization of GHsecreting adenoma and mature bone tissue, and (c) co-localization of GH-secreting adenoma and nerve bundles. In this study, immunoreactivity for nestin was observed in these three different phenotypes of GH-secreting adenomas, not only in perivascular spaces of pituitary tumor vessels but also in parenchymal cells of the pituitary adenoma.
Conclusion: Various kinds of cells can differentiate from the stem cells in GH-secreting adenomas, which may result in plurihormonality and pluripotentiality of adenomas.
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