Hormonal evidence for the dissemination through the cerebrospinal fluid, of secreting cells from invasive pituitary adenomas.

In 13 patients with invasive pituitary adenomas submitted to pituitary surgery (5 HGH-secreting adenomas, 6 prolactin-secreting adenomas, 2 non-secreting adenomas), the concentrations of HGH and prolactin (PRL) constantly decreased after operation both in the cerebrospinal fluid (CSF) and serum, and the CSF/serum ratio remained under one, with few exceptions. These last cases (2 with acromegaly, 2 with invasive prolactinomas), showed an increase of HGH or PRL concentrations in CSF when serum levels decreased; the CSF/serum ratio rose above one within 2 weeks post surgery in 2 patients, and within 2 years post surgery in another two. The circulation of CSF was not obstructed. This indicated the appearance of a new, extrapituitary source for secreting HGH or PRL directly into the CSF, a source which most probably developed through the dissemination, via CSF, of secreting cells from malignant pituitary adenomas.