Mc. Vantyghem et al., IMMUNOHISTOCHEMICAL DETECTION OF GLYCOPROTEIN HORMONE ALPHA-SUBUNIT IN SOMATOPROLACTINIC AND PURE SOMATOTROPH ADENOMAS, Journal of endocrinological investigation, 21(7), 1998, pp. 434-440
Glycoprotein hormone alpha subunit (alpha SU) is expressed in nearly a
ll thyreotroph adenomas and most gonadotrophinomas, but is less well d
ocumented in plurisecreting adenomas. We therefore examined the immuno
histochemical (IHC) expression of alpha SU in a generally accepted mod
el of plurisecreting adenomas (somatoprolactinic type) by comparison t
o a series of pure monosecreting somatotroph tumors. Fifty patients (3
2 females, 18 males) aged 15 to 68 years with clinical and/or biologic
al acromegaly requiring adenomectomy were studied. Forty-five had clin
ical acromegaly and 5 had isolated amenorrhea and/or galactorrhea synd
romes. Forty-eight of the 49 patients who had baseline assessments of
plasma GH had a mean concentration of 5 ng/ml or more (normal value <5
). Fifteen of the 46 patients who had baseline measurements of plasma
PRL had a prolactinemia value greater than 20 ng/ml (normal value <20)
but below 100 ng/ml, except for one patient. All the adenomas studied
were positive by GH immunohistochemistry; 21 were immunostained by an
antiPRL antibody and formed the ''somatoprolactinic'' (GH-PRL) group.
Five of these 21 patients were male. The 12 female patients younger t
han 50 years had amenorrhea or galactorrhea, and one male patient comp
lained of impotence. Eleven patients (9 females, 2 males) in this GH-P
RL group had hyperprolactinemia. Sixteen of these GH-PRL adenomas were
immunolabeled by alpha SU antiserum. The remaining 29 adenomas, which
were immunonegative with the PRL antibody and formed the ''somatotrop
h adenoma'' (GH) group, were more frequent in male patients (13/29; 45
%) compared to GH-PRL group. Eight amenorrhea or galactorrhea syndrome
s occurred among the 14 women younger than 50 years, 3 of whom had hyp
erprolactinemia. Thirteen of these 29 adenomas (45%) were immunopositi
ve with aSU antibody. Compared to the GH group, the GH-PRL group had a
significant higher frequency of amenorrhea and/or galactorrhea syndro
mes among women under 50 years (100% vs 57%; p<0.01), as well as hyper
prolactinemia (55% vs 15%; p<0.01) and positive aSU immunoreactivity (
76% vs 45%; p<0.05). The frequency of extrasellar macroadenomas was no
t different according to PRL or alpha SU immunoreactivity. Thus, in th
is series of somatoprolactinic adenomas, alpha SU immunopositivity was
slightly more frequent than in a control group of pure somatotroph ad
enomas. Moreover, hyperprolactinemia was more frequent in patients wit
h GH-PRL adenomas, although the size of the pure and mixed adenomas wa
s not different. These results suggest that hyperprolactinemia and/or
alpha SU immunopositivity are more often associated with mixed GH-PRL
adenomas. (J. Endocrinol. Invest. 21: 434-440, 1998) (C)1998, Editrice
Kurtis