抄録
Forty patients with growth hormone (GH) -secreting pituitary adenomas were included in a histological and endocrinological investigation. Thirteen were found to have hyperprolactinemia. Light and electron microscopic studies showed no morphological differences between the adenomas of patients with and without hyperprolactinemia. Neither mammosomatotroph cell adenoma nor acidophil stem cell adenoma was detected in GH-secreting pituitary adenomas associated with hyperprolactinemia. Immunohistochemical study revealed 90% of the tumors to contain prolactin (PRL)-positive cells, in both patients with hyperprolactinemia and those with normal PRL values. These findings suggest that GH-secreting pituitary adenoma might more accurately be termed “mixed GH cell-PRL cell adenoma.” In addition, there was a statistically significant correlation between the preoperative serum PRL values and the proportion of immunoreactive PRL-secreting in the tumor cells (p <0.05) . Among the 13 hyperprolactinemic patients, three whose tumors contained few or no immunoreactive PRL-secreting cells were nonresponders to thyrotropin releasing hormone (TRH). In one of these patients the tumor protruded into the suprasellar region and the suspected cause of the hyperprolactinemia was interference with the release of prolactin inhibitory factor. In the other two patients the hyperprolactinemia could not be explained. The remaining 10 hyperprolactinemic patients responded to TRH and their tumors contained many immunoreactive PRL-secreting cells. Thus, it appears that in TRH responders the hyperprolactinemia was attributable to PRL secretion within the tumor.
