SAT-475 PRL Secreting Macroadenoma and Development CSF Leak Secondary to Cabergoline Use

Background: Macroprolactinomas are normally managed with dopamine agonists, resulting in tumor shrinkage and normalization of prolactin. Occasionally they can invade the skull base, erode the sellar floor, and extend into the sphenoid sinuses. Rarely, dopamine agonist therapy can result in spontaneous CSF leak and rinorrhea. We present a case of cabergoline associated CSF leak. Case Presentation: A 46 y.o. man was diagnosed with a macroprolactinoma after evaluation of fatigue associated with low testosterone. He denied headaches and his gross visual fields were intact. His prolactin was 4916 ng/mL (nl 4-15.2 ng/mL) and MRI showed a large sellar and suprasellar mass, 2.5 x 3.5 x 3.1 cm, extending into the interpeduncular cistern and cavernous sinus while compressing the optic chiasm and right cerebral peduncle. He was started on Carbergoline 0.5 mg, 5 days a week for 2 weeks, then 4 days a week. His serum prolactin declined to 291 ng/mL in 4 weeks. He reported having headaches on the days when he took it but denied rhinorrhea or visual field changes. Two months after treatment began he noticed clear fluid draining from his left nare. It was intermittent and occurred with head movement. He denied headache, photophobia, or neck stiffness. He was instructed to go to the ED for suspicion of a CSF leak. On examination, clear drainage was observed from his left nare. CT and MRI showed shrinkage of the macroprolactinoma with CSF filling the space, and a clear path connecting brain and sinuses, allowing for flow of CSF. Rhinorrhea was collected and sent for glucose, protein, and beta 2 transferrin. Glucose was elevated at 79mg/dL (nl 40-70 mg/dL), protein elevated to 78.4mg/dL (nl 15-45 mg/dL) with beta 2 transferrin detected (nl undetectable). Neurosurgery and ENT evaluation revealed evidence that the prolactinoma had put pressure on his sinuses with resulting bone remodeling allowing communication between his brain and sinuses. This allowed CSF to flow freely through the left nare once the pressure of the prolactinoma was released and space was replaced with CSF. He underwent endoscopic resection of his pituitary tumor, bilateral nasal endoscopy with repair of the CSF leak, and a fat graft. Conclusion: Cabergoline induced CSF rhinorrhea is a rare but life-threatening complication carrying a high risk of ascending meningitis. It can occur within the first few weeks to several months of treatment, and it may be misdiagnosed as allergic rhinitis, sinusitis or the common cold. CSF rhinorrhea can be differentiated from other conditions by fluid analysis for glucose and beta-2 transferrin. Close follow-up and high suspicion for CSF leak should be maintained in patients with invasive prolactinomas where the tumor may be more likely to affect bony architecture.