Abstract
In this study, the central technique of in vitro culture has been used to further investigate whether LH/FSH-expressing, but clinically
“functionless” pituitary adenomas are gonadotropinomas or whether their hormone secretion
is due to transdifferentiation events. 664 “functionless” pituitary adenomas were
examined for hormone secretion by in vitro culture and for hormone content by immunostaining. The results were correlated with
the clinical findings. 40 % of the tumours (n = 263) secreted at least one of the
gonadotropins alone, 8 % (n = 53) exhibited various patterns of anterior pituitary
hormones, whilst the remaining 52 % of tumours were not associated with any hormone.
In the secretory tumours, immunostaining revealed only a few scattered hormone-containing
cells (5 to 15 %). Mild hyperprolactinaemia was observed in some cases, presumably
because of pressure effects of the tumours. The majority of the patients suffered
clear cut hypopituitarism (p < 0.05). Pre-operatively, gonadotropin hypersecretion
was observed in 3 cases, but only one of these secreted hormones in culture. Interestingly,
a higher proportion of tumours removed from patients with hypopituitarism showed secretory
activity in vitro than those tumours removed from patients showing no hormonal dysfunction or hyperprolactinaemia.
We conclude that the term “gonadotropinoma” to describe functionless pituitary tumours
associated with LH and/or FSH secretion is a misnomer, because the presence of LH
and/or FSH confirmed by in vitro methods in the present series is a result of only a few scattered cells. We suggest
that primary pituitary tumour cells differentiate into a secretory type (transdifferentiation),
possibly in response to altered serum hormone levels such as decreased steroids. Further
work is required to identify the factors which trigger the altered cells' characteristics.
Key words
Pituitary adenoma - hypopituitarism -
in vitro
- gonadotrophinoma transdifferentiation
References
in vitro and in culture.
J Clin Endocrinol Metab.
1985;
61
1061-1065
buchfelder@med.uni-goettingen.de
