Cerebrospinal Fluid Leak After Medical Management of Prolactinoma

Introduction: Dopaminergic agonists such as cabergoline are commonly used to treat prolactinomas, and often lead to significant adenoma shrinkage. Rarely, macroprolactinomas may invade the sphenoid sinus and pose a therapeutic challenge, as treatment with dopamine agonists and subsequent tumor shrinkage can lead to a cerebrospinal fluid (CSF) leak. Clinical Case: A 32-year-old female with no prior medical history presented to the emergency room of an outside hospital for headaches and visual changes. MRI demonstrated a 4.3 x 4.0 x 3.0 cm sellar mass with extension into the right cavernous sinus and sphenoid sinus, and prolactin was elevated to 1,859 ng/ml (3.4 - 21.4). Cabergoline was initiated at a dose of 0.25 mg twice a week with a decrease in her prolactin to 646 ng/ml one month later. Six months after initiation of therapy she transferred her care to our institution and presented for a routine endocrinology visit. She complained of rhinorrhea worse when upright that had begun two weeks prior to this encounter. Urgent MRI of the sella revealed an interval decrease in the size of the sellar mass to 2.1 x 2.7 x 1.5 cm and a fluid collection extending from the sella turcica to the left sphenoid sinus consistent with a CSF leak, and labs showed a prolactin level of 169 ng/ml. Cabergoline was discontinued and the patient was admitted to the hospital for treatment with antibiotics and acetazolamide. She underwent lumbar drain placement while awaiting definitive surgical management, which was delayed due to the COVID-19 pandemic. While off cabergoline, the sellar mass increased in size and her prolactin rose to 1,449 ng/ml, with no effect on the optic chiasm and visual fields. Three months later, she underwent transsphenoidal debulking of the pituitary mass with repair of the sellar floor and removal of lumbar drain. Her postoperative course was uncomplicated and she resumed cabergoline 0.25 mg twice weekly. A prolactin measured two weeks postoperatively was 337 ng/ml. Tumor histopathology revealed a 1.3 x 0.4 x 0.3 cm pituitary adenoma. Immunohistochemistry stained positive for chromogranin A, synaptophysin, and prolactin only. An MRI of the sella and prolactin level will be repeated at her next endocrinology visit. Conclusions: CSF leak is a rare but serious complication from tumor shrinkage after medical management of large invasive prolactinomas, and patients with such tumors should be monitored closely for its development. CSF leaks can increase a patient’s risk for meningitis and subsequent morbidity and mortality. The management of patients with large prolactinomas with local invasion should involve a multidisciplinary approach for decision making, extensive patient education, and close follow up in order to identify and treat a CSF leak should it develop.