A 46 year old female presented with 12 months history of secondary amenorrhoea. Prolactin was 4746 mIU/l without macroprolactin complexes, LH & FSH were low, oestradiol was undetectable. She had normal visual fields. No other clinical or biochemical features of pituitary dysfunction. She had no regular medication. Pituitary MRI was normal. 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. Compliance with medication was confirmed. Repeat pituitary MRI scan was normal. An alternative source of prolactin was considered. 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 reduced to 59 mIU/l and menstrual cycle returned.
Discussion: The notable features of this case were (1) the high prolactin with a normal MRI scan (2) A paradoxical rise in the serum prolactin after initiation of dopamine agonist therapy. Out of 8 previous reports of ectopic extra-cranial prolactin secretion in the published literature, there were three ovarian germ cell tumours (two teratomas, one dermoid) which showed microscopic pituitary elements. UTROSCTs are rare uterine neoplasms with the most recent 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 rare. Where suspected, the majority of ectopic prolactin-secreting tumours have been located in the ovaries and uterus.