Endocrine Abstracts

Introduction: Cystic prolactinoma, a variant of prolactin-secreting pituitary adenoma, presents ongoing debate regarding the most effective first-line treatment strategies. While dopamine agonists are known to offer considerable clinical improvement and tumor shrinkage, potentially reducing the need for surgery, the optimal approach remains uncertain. We present a patient with cystic macroprolactinoma who had TSA for persistent visual field defect despite excellent biochemical response to dopamine agonist treatment.

Case: A 26-year-old woman was diagnosed with a 3.3 cm cystic macroprolactinoma following 12 months of galactorrhoea and secondary amenorrhea. Serum prolactin at presentation was 20,193 mIU/L (monomeric prolactin 14,760, ref range 109-557). Her IGF1 was normal 7.4 nmol/l (10.3 – 39.6). She had a left homonymous hemianopia at diagnosis. Her prolactin fell to 7281 mIU/L 6 weeks after initiation of cabergoline. Despite this reduction, her visual field deficit persisted, leading to the decision to offer transsphenoidal surgery (TSA). During TSA, extensive cavernous sinus involvement was noted. The histology found a lactotroph adenoma with strong cytoplasmic cam 5.2 expression, and low proliferation index (MIB1 1-2%). Four weeks post-TSA, her prolactin reduced to 835 mIU/l. Post operative MRI at 3-months showed a reduction in the size of the pituitary adenoma and decompression of optic chiasm. Postoperatively, her visual field deficit improved significantly. Cabergoline treatment was continued for the residual disease.

Discussion: This case highlights the importance of careful consideration of both medical and surgical treatment options in patients with prolactinomas with large cystic components. TSA may be considered as a first line option for cystic macroprolactinomas with significant visual impairment.