Endocrine Abstracts

Introduction: Dopamine agonist resistance is rare in prolactinoma (10%). Doses of cabergoline of up to 2.0 mg/week are usually effective in controlling prolactin (PRL) secretion and reducing tumor size. Surgical treatment is rarely indicated.

Case report: An 18-year-old female presented in 2002 with a 2-year history of amenorrhea and galactorrhea. Hormonal investigation showed a hyperprolactinemia (4800 mUI/l) with integrity of the other pituitary axis. The acromegaly was excluded. The magnetic resonance imaging (MRI) revealed a 2 cm pituitary adenoma with suprasellar extension. The visual field showed central bilateral scotoma.

The patient was initiated on bromocriptine, which was titrated to a daily dose of 15 mg. Subsequent MRI showed a decrease in the pituitary mass to 11 mm but PRL never normalized during 6 years of bromocriptine and ranged from 1677 to 3074 mUI/l.

In 2010, she switched to cabergoline, which was titrated to a weekly dose of 2.5 mg. Subsequent MRI showed no amelioration, prolactin never normalized and the patient was always in amenorrhea, despite compliance to cabergoline and increasing to a weekly dose of 6 mg.

Finally, she was referred to neurosurgery and she underwent a transsphenoidal endoscopic resection of the pituitary adenoma. The immunohistochemical analysis demonstrated positive staining for PRL (+++) and LH(+). Ki-67 nuclear labeling was estimated at 1%.

The patient had no postoperative complications, with integrity of corticotrope and thyretrope axis. But 3 months after the surgery, she had no resumption of menses and the hormonal exploration showed a hyperprolactinemia (2668 mUI/l). The serum HCG level was elevated. A spontaneous pregnancy of 13 weeks of amenorrhea was diagnosed.

Conclusion: Although rarely indicated, the surgical treatment is interesting in resistant prolactinoma, especially in young woman with infertility.