LAUSR

BackgroundDopamine agonists are the standard first-line medical therapy for prolactinoma. We report a rare case of giant prolactinoma with a first epileptic seizure due to rapid reduction of the tumor as a complication of dopamine agonist therapy.Case presentationA 27-year-old Japanese man presented to our institution with a history of visual disturbance for 1 year and general fatigue for 3 months. Magnetic resonance imaging showed a tumor that arose from the pituitary and extended to the bilateral anterior skull base, the clivus, and the cavernous sinus, with compression of the optic chiasm and the bilateral frontal and temporal lobes. On the basis of the patient’s serum concentration of prolactin, we diagnosed a prolactinoma and started dopamine agonist therapy with cabergoline. The patient had a general seizure immediately after starting dopamine agonist therapy and required general anesthetic treatment following the rapid reduction of the tumor. We speculated that the rapid reduction of the tumor resulted in the retraction of the surrounding brain structure, and the epileptic seizure was then induced by dopamine agonist therapy.ConclusionsWe report a rare case of giant prolactinoma with a first epileptic seizure immediately after the initiation of dopamine agonist therapy. Clinicians need to be aware that the rapid reduction of a giant prolactinoma by dopamine agonist therapy may cause an epileptic seizure.