Cerebrospinal fluid rhinorrhea secondary to cabergoline therapy in an invasive macroprolactinoma: case report and review of the literature

Abstract

Prolactinomas account for approximately 45% of pituitary tumors, and dopamine agonists are the first-line treatment. A rare but potentially serious complication of this therapy is cerebrospinal fluid (CSF) leakage, resulting from rapid tumor shrinkage that exposes pre-existing bony and dural defects. We report a case of cabergoline-induced CSF leak in an invasive macroprolactinoma and review key pathophysiological and therapeutic aspects. Case report: A 39-year-old man presented with longstanding migraine-like headaches, decreased libido, and erectile dysfunction. Magnetic resonance imaging revealed an invasive macroprolactinoma (32×25×22.5 mm) involving the right cavernous sinus (Knosp 4) with pituitary stalk deviation; initial prolactin was 1325 ng/mL. Cabergoline 1 mg/week was initiated, leading to rapid clinical improvement and a marked prolactin decline. One month later, he developed continuous unilateral watery rhinorrhea, worsened by leaning forward. Magnetic resonance imaging showed tumor shrinkage with sphenoid sinus involvement. CSF leak was confirmed, and the patient underwent successful endoscopic endonasal repair. He recovered without recurrence, with sustained biochemical control and a stable residual lesion on follow-up imaging. Conclusions: dopamine agonists-induced CSF rhinorrhea occurs in 5-13% of invasive macroprolactinomas, particularly in large tumors with supra- and infrasellar extension and prolactin levels >1000 ng/mL. Given the significant risk of meningitis, early clinical suspicion and prompt endoscopic surgical repair are essential. Conservative management is rarely effective.