MON-060 A Case of Invasive Prolactinoma Leading to CSF Leakage and Intracranial Hypotension

Abstract Disclosure: K. Purewal: None. J. Kahlon: None. Prolactinomas are the most common type of pituitary adenoma and can be further classified by size. A giant prolactinoma measures greater than 40mm and comes with its own unique challenges in management. These tumors have the ability to invade nearby structures which can lead to rare complications such as CSF leakage particularly if there is erosion of the sellar floor. The patient is a 38 year old male with a benign medical history brought to the ED after a new onset seizure. MRI Brain revealed a 6.4cm x 4.4cm large sellar mass invading into the right cavernous sinus. There was also invasion into the right optic canal and right petrous apex along with encasement of the right ICA. Patient reported having right sided visual deficits, gynecomastia, galactorrhea, and low libido. The PRL level was 10,057 ng/mL with diluted PRL of 9,727 ng/mL. The case was discussed with neurosurgery and given the extent of disease the patient was started on cabergoline .5mg twice weekly. The patient was then discharged home with outpatient follow up. The patient was re-admitted after 3 completed doses of cabergoline with symptoms of rhinorrhea concerning for CSF leak. A repeat MRI brain was done which showed a reduction in size of the prolactinoma to 4.4cm x 3.7cm. The patients PRL had fallen from 10,057 to 737 ng/mL. During the hospitalization the patients rhinorrhea spontaneously resolved and he had no spinal headache symptoms. He was discharged with a reduced dose of cabergoline .25mg once weekly. The patient ultimately had a third admission 2 weeks after initiating cabergoline therapy with confusion and right sided hemiparesis. Imaging at the time showed pneumocephalus, the prolactinoma eroding into the sphenoid sinus, and a left parafalcine hematoma. The hematoma was believed to result from venous infarction caused by significant CSF loss and subsequent brain sagging. The patient underwent transphenoidal debulking of the mass with placement of abdominal fat over the leak area. There were no post-operative complications and he was discharged with .5 mg of cabergoline weekly.This case illustrates how a giant prolactinoma can present with a range of unique challenges that requires a multidisciplinary approach. As seen in this case, cabergoline can lead to rapid regression of the tumor with rare consequences such as CSF leakage. This leakage can lead to a sequelae of problems including intracranial hypotension, brain sagging syndrome, and venous infarction with hemorrhage. Presentation: Monday, July 14, 2025