[Pituitary adenomas of patients with galactorrhea. Light and electron microscopic studies (author's transl)].

A collection of 108 surgically removed pituitary adenomas was studied by histologic, immunohistochemical and electron microscopical methods. It included 7 predominantly chromophobe adenomas of patients whose clinical symptoms consisted of a pure galactorrhea. Ultrastructurally, 4 of these adenomas contained little endoplasmic reticulum so that an endocrine activity of the tumors could not be assumed. These cases represented inactive adenomas which probably led to a disturbance of the secretion of prolactin-inhibiting factor by suprasellar extension resulting in stimulation of the non-tumorous adenohypophysis and secondary hyperprolactinemia. Another 3 adenomas consisted of cells that showed histologic and immunocytochemical reactions of the same kind as normal prolactin cells. Electron microscopically, these adenoma cells exhibited a very well developed rough-surfaced endoplasmic reticulum, dilatation of the Golgi complexes, sparsely arranged pleomorphic secretory granules, an increased number of microtubules, and interdigitating microvilli formed by the cell membrane. These features resembled closely the characteristics of stimulated non-tumorous prolactin cells during lactation, and thus could be termed "prolactin cell adenomas". These tumors surely caused a hyperprolactinemia through their own hormone production. In addition 3 other adenomas were present which showed the same light and electron microscopic structures as the prolactin cell adenomas but did not cause galactorrhea. From the findings in these cases we assume that the tumors effected neither a clinically peculiar hyperprolactinemia nor produced an endocrinologically inactive polypeptide.