SAT-476 A Case of Rathke's Cleft Cyst Presenting with Hyperprolactinemia

CASE: A 15 year-old G0P0 female with no significant PMH was referred to Endocrinology for oligomenorrhea and hyperprolactinemia. Menarche was at age 13 and she subsequently had oligomenorrhea for a year. She endorsed headaches and fatigue upon climbing a flight of stairs but denied vision changes, galactorrhea, hirsutism, SOB, and constipation. She was not on any psychotropic medications.The patient was hemodynamically stable with a normal physical examination including affect and cognition. Labs revealed prolactin-402 ng/mL (N=3-24 ng/mL), monomeric prolactin-277 ng/mL (macroprolactin=31%), cortisol-9.2 ug/dL one hour after cosyntropin, and DHEA-54.8 ug/dL (N=110-433.2ug/dL). TSH, LH, FSH, sex hormone binding globulin, testosterone, HCG, insulin-like growth factor, 17OH-progestereone were all within normal limits. MRI with and without contrast revealed a 1.5 x 1.8 x 1.8cm sellar lesion with characteristics most consistent with Rathke’s cleft cyst (RCC) with mass effect on the infundibulum and optic chiasm. The patient was started on cabergoline 0.25mg twice a week and Neurosurgery was consulted. Surgical resection was recommended. DISCUSSION: We present a rare case of symptomatic hyperprolactinemia in an adolescent female with radiologic evidence of RCC. RCC is an uncommon and usually asymptomatic intrasellar lesion, but pituitary dysfunction has been reported in 39% to 100% of these cases with prolactin levels generally less than 200 ng/mL. This hyperprolactinemia has been postulated to occur due to pituitary stalk compression from the sellar mass causing a decrease in dopamine (prolactin inhibitor) delivery. Possible explanations for RCCs with grossly elevated prolactin levels include: (1) coexisting pituitary adenoma, (2) cystic adenoma, and (3) pituitary stalk effect. (1) and (2) are the simplest explanations but radiologic features of adenomas were not seen on MRI. In our case, prolactin was higher than the typical levels seen in stalk compression raising concern for either coexisting pituitary adenoma or cystic adenoma although these are rare. This finding combined with hypocorticolism and radiologic evidence of mass effect warranted surgical intervention. CONCLUSION: Symptomatic RCC is rare, but clinicians should be aware that hyperprolactinemia is common in these cases. The degree of hyperprolactinemia may help guide decisions about further diagnostic evaluation and treatment. REFERENCES: 1. Eguchi K, Uozumi T, Arita K, et al. Pituitary function in patients with Rathke’s cleft cyst: significance of surgical management. Endocrine Journal. 1994; 41: 535-540. 2. Isono M, Kamida T, Kobayashi H, et al. Clinical features of symptomatic Rathke’s cleft cyst. Clin Neurol Neurosurg. 2001; 96-100. 3. Voelker JL, Campbell RL, Muller J. Clinical, radiographic, and pathological features of symptomatic Rathke’s cleft cyst. J Neurosurg. 1991; 74: 535-544.