SUN-285 Too Big to Be True, Too Young to Stroke!

BACKGROUND: Lactotroph adenomas are the most common type of pituitary adenomas and can cause infertility and menstrual irregularities in women; hypogonadism and gynecomastia in men.(1) Giant prolactinomas are an unusual subset of pituitary macroadenomas with limited literature available on their management.(2) We describe an unusual case of giant prolactinoma in a young man who presented with symptoms of stroke, that reversed with treatment with cabergoline. Clinical Case: 25-year old man presented with gradually progressing upper extremity weakness for evaluation of stroke. He reported stumbling into things when walking. There was a question of left sided facial droop and Bell’s palsy in recent past. He reported recent weight gain and erectile dysfunction. He was noted to have left homonymous hemianopsia on exam in addition to left upper and lower extremity weakness. MRI Brain showed an enormous mass that filled the sella turcica, invaded the sphenoid sinus and right side of the skull base, invaginating deep into the base of the right cerebral hemisphere with mass effect on the pons, right-sided midbrain, right temporal lobe and right basal nuclei, measuring 6.3 X 5.5 x 7.5 cm. Pituitary hormonal evaluation showed elevated prolactin (PRL) level with dilution at 13,580 ng/mL, with low testosterone (T) level (total T 42 ng/dL, free T 10 pg/mL, SHBG 15 nmol/L). Thyroid and adrenal axes were intact with normal IGF-1 level. In view of very high PRL level, he was started on cabergoline 0.5 mg daily initially and decreased to every other day after 2 weeks as PRL level began to decline. In 8 months, PRL levels decreased to 1293.07 ng/dl (90% reduction) and prolactinoma decreased to 6.0 x 3.7 x 4.7 cm (56% volume reduction). Total and free T improved to 134 ng/dL and 31 pg/dL respectively. He experienced marked improvement in left hemianopsia, with resolution of weakness and slurred speech. Energy level and erectile dysfunction improved. Currently he is being maintained on 0.5 mg cabergoline every other day Conclusion: Giant prolactinomas are uncommon and can present with compressive symptoms, that can be mistaken as stroke. Treatment with anticoagulation may cause hemorrhage and apoplexy with worsening of symptoms.(1,2) There is limited data available regarding first line therapy for giant prolactinomas with 2 case reports where giant prolactinomas have been treated effectively with cabergoline.(3,4) It is important to recognize the cause of such symptoms, and treated where possible with effective medical therapy to prevent morbidity. References: 1. Moraes A et al., Giant prolactinomas: the therapeutic approach. Clin Endo (Oxf). 2013 Oct;79(4):447-56 2. Acharya SV et al., Giant prolactinoma and effectiveness of medical management. Endocr Pract. 2010 Feb;16(1):42-6 3. Ahmed, M, et al., Large Prolactinoma. NEJM 2010; 363:177 4. Masoud, R et al., Giant prolactinoma: case report. J Diabetes Metab Disord. 2013; 12: 3