ACTA ENDOCRINOLOGICA (BUC)

Background. Dopamine agonists (DA) are first line treatment for prolactinomas. Optic chiasm herniation can rarely occur during therapy, while brain herniation is very uncommon. Case Reports. A 34 yo woman presented with headaches and vision changes. Prolactin (PRL) was 4300 ng/ mL. MRI showed a 4.5 cm pituitary adenoma with chiasm compression. After 3 months, PRL decreased to 201 ng/ mL while patient was taking CAB 0.75 mg twice a week. MRI showed ~30% tumor reduction with medial temporal lobe herniation and encephalocele. CAB was stopped and she underwent surgical debulking and encephalocele repair. Histopathology confirmed prolactin tumor. CAB 0.75 mg twice a week was resumed. A 50 yo man had incidental detection of a sellar mass after trauma. MRI showed 3.6 cm tumor with minimal contact of right optic nerve, and PRL 3,318 ng/ml. He received CAB 0.5mg twice a week with PRL improvement to 26 ng/mL after 1 month. After 2 months ophthalmology exam showed new left superotemporal depression. PRL was 68 ng/mL and MRI showed 35% mass reduction and new inferior displacement tethering of the chiasm. CAB dose was decreased to 0.25 mg twice a week. Conclusion. Our cases illustrate that rapid biochemical and radiographic response to DA therapy in large prolactinomas warrants close clinical and neuroophthalmologic follow-up. We recommend repeating the MRI 3 months after initiation of DA therapy or sooner in case of new mass effect manifestations. Decision regarding DA dose reduction or chiasmopexy for visual field deficits needs to be multi-disciplinary and on a case-to-case basis.