EndocrineUpdate2018-Hyperprolactinaemiaresistanttodopamineagonistduetoanectopicsourceofprolactin.pdf (190.62 kB)
Hyperprolactinaemia resistant to dopamine agonist due to an ectopic source of prolactin arising from a Uterine Tumour Resembling Ovarian Sex Cord Tumours (UTROCST)
journal contribution
posted on 2018-06-15, 17:52 authored by Mohamed Bakhit, Sobia Arshad, John Bidmead, Masud Haq, Dylan Lewis, Salvador J. Diaz-CanoSalvador J. Diaz-Cano, Simon J. B. AylwinIntroduction:
Moderate hyperprolactinaemia occurring in a patient with a normal
pituitary MRI, assuming macroprolactin and stress are excluded, is
generally considered to be due to a lesion below the level of detection
of the MRI scanner. Most patients with mild-moderate hyperprolactinaemia
and a normal MRI respond to dopamine agonist therapy. We describe a
patient who had prolactin elevation typical of a prolactin-secreting
macroadenoma, but with a normal MRI, and in whom the prolactin rose
further with dopamine agonist treatment.
Case: A 46 year-old female presented with 12 months history of secondary
amenorrhoea without galactorrhoea. Prolactin was 4746 mIU/l without
macroprolactin complexes, LH & FSH were low and oestradiol was
undetectable. She had normal visual fields and no other clinical or
biochemical features of pituitary dysfunction. She was not on regular
medication. Pituitary MRI was normal with no focal lesion. She was
started on cabergoline 250 mcg twice weekly which was subsequently
increased to 500 mcg twice weekly. Repeat serum prolactin 5 months and 8
months later showed a progressive rise to 6649 mIU/l and 9653 mIU/l
respectively, and rose to 11,611 mIU/l. Compliance with medication was
confirmed. Repeat pituitary MRI scan was normal. An alternative source
of prolactin was considered and further clinical assessment revealed a
palpable pelvic mass. Pelvic CT showed an 11 cm uterine mass which
raised the possibility of an ectopic prolactin source. She underwent
surgical resection. Histological examination showed a benign Uterine
Tumour Resembling Ovarian Sex Cord Tumours (UTROSCT).
Immunohistochemistry was negative for prolactin, however, serum
prolactin postoperatively was 59 mIU/L and her menstrual cycle returned
to normal.
Discussion: The notable features of this case were (1) the high
prolactin suggestive of a macroadenoma with a normal MRI scan (2) a
paradoxical rise in the serum prolactin after initiation of dopamine
agonist therapy. Out of eight previous reports of ectopic extra-cranial
prolactin secretion in the published literature, there are three ovarian
germ cell tumours (two teratomas, one dermoid) which had microscopic
pituitary elements. UTROSCTs are very rare uterine neoplasms with the
most literature review citing 77 cases. UTROSCTs have not been
associated with hyperprolactinaemia prior to this report. However, two
other cases have been reported with uterine tumours (one “fibroid” and
one “mesenchymal tumour”) which share characteristics with this case.
Hyperprolactinaemia due to extra-cranial ectopic prolactin production is
very rare. Where suspected, the majority of ectopic prolactin-secreting
tumours have been located in the ovaries and uterus.