SUN-099 - When Dopamine Agonists Must Wait: A Giant Prolactinoma Requiring Urgent Surgical Decompression

Dopamine agonists are the first-line therapy for prolactinomas, including large tumors. However, acute neurologic deficits may necessitate immediate surgical intervention and leave no window for initial dopamine agonist therapy.
We present a 22-year-old Filipino male with a one-year history of progressive fatigue, weight loss, decreased libido, and visual decline. Initial laboratory workup revealed central hypothyroidism (low FT4 with inappropriately normal) and severe vitamin D deficiency. 8 am serum cortisol, and a repeat thyroid panel were requested but the patient was lost to follow-up.
2 months later, he again consulted with worsening weakness and was noted to have hypocortisolism (serum cortisol 2.94 µg/dL) and persistent central hypothyroidism. He sought consult with a neuro-opthalmologist where magnetic resonance imaging revealed a massive sellar-suprasellar tumor measuring 6.3 cm in its largest dimension with cavernous sinus invasion (Knosp grade 4), encasement of intracranial vessels, compression of the optic apparatus, and a large tumoral hemorrhagic component (computed volume of 62 mL) causing midline shift and hypothalamic compression. Given the extent of mass effect and progressive visual impairment with no light perception on the right eye, he was immediately referred to neurosurgery.
Further hormonal evaluation demonstrated marked hyperprolactinemia (13,970 ng/mL), hypogonadotropic hypogonadism, and low IGF-1, consistent with panhypopituitarism. The patient was started on glucocorticoid and thyroid hormone replacement. Due to the urgency of the procedure, there was no therapeutic window for initial dopamine agonist therapy. The patient underwent right pterional craniotomy with tumor debulking with no post-operative complications.
Postoperatively, he demonstrated clinical improvement, including resolution of headaches and improved energy. Dopamine agonist therapy (cabergoline) was initiated after surgery, resulting in a marked decline in prolactin levels to 290 ng/mL on follow-up 1 week post-op. One month post-operatively, prolactin levels declined to normal at 13.60 ng/mL with no recurrence of headaches. He reports no progression of visual field deficits.
This case highlights a rare but critical scenario where primary surgical management may precede dopamine agonist therapy in the management of a giant prolactinoma. While medical therapy remains the standard of care, clinicians must recognize cases where delay in decompression may result in irreversible neurologic damage. Early recognition is essential to guide timely, vision saving intervention.

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