ODP328 Longitudinal Multidisciplinary Approach for Cabergoline-Resistant Aggressive Prolactinoma Complicated by Multiple Endocrine Neoplasia Type 1

BACKGROUND: Cabergoline-resistant prolactinomas comprise approximately 10% of all prolactinomas, and sometimes show aggressive features including invasion or higher proliferation profiles. The treatment for such cabergoline-resistant aggressive prolactinomas is challenging and requires a multidisciplinary approach. Clinical case: A 47-year-old woman was diagnosed with hyperprolactinemia after complaining of menstrual irregularities at 20 years old. No neoplastic lesion was identified in the suprasellar region, and 0.25 mg/week cabergoline was initiated. At 35 years’ old, an adenoma was suspected on the right side of the pituitary gland, though plasma prolactin values were sustained without any clinical symptoms. When the patient was 46 years old, her prolactin levels elevated to 202 ng/ml, and magnetic resonance imaging showed a tumor invaded bilateral cavernous sinuses. Because prolactin levels and tumor size continued to increase despite increasing the cabergoline dose to 1 mg/week, endoscopic transsphenoidal surgery was performed. The tumor nearly total removal, the postoperative prolactin levels decreased to 00, but started to increase again in a short period of time. Pathologic assessment revealed a high Ki-67 index (20%) and diffusely positive prolactin alongside negative expression of other anterior hormones. The tumor remained in the cavernous sinus and postoperative prolactin levels tended to increase over time. Cabergoline was restarted and increased to 7mg/week, although prolactin levels were not suppressed. Magnetic resonance imaging and computed tomography scanning showed no metastasis, and octreotide scintigraphy revealed no abnormal accumulation except for the tumor in the cavernous sinus. Radiation therapy was administered to the remaining tumor, and prolactin levels gradually decreased. Thereafter, hypercalcemia and high intact parathyroid hormone levels were found in the presence of left-inferior parathyroid enlargement, leading to a diagnosis of multiple endocrine neoplasia type 1 (MEN1). The patient had no family history of endocrine disease. MEN1 gene mutation was not detected by direct sequencing. DISCUSSION: Functional pituitary adenomas including prolactinomas and growth hormone-producing pituitary adenomas are usually benign with a Ki-67 index of approximately 1%, little mitosis, and slow progression 1) . However, pituitary adenomas in MEN1 patients have a higher rate of drug resistance and histological invasiveness than sporadic adenomas, which results in a higher postoperative recurrence rate and a lower normalization rate of approximately 40% 2) . For this case, close monitoring for tumor growth and metastasis was essential. References: 1) KontogeorgosG Endocrine 2005;27-352) Verges B, et al. J Clin Endocrinol Metab 2002; 87: 457-465. Presentation: No date and time listed