ODP337 Neurenteric Cyst Apoplexy with Post-Operative Diabetes Insipidus in a 14-year-old Male

BACKGROUND: Apoplexy of benign neurenteric cysts can present with acute onset of a severe headache. Pituitary dysfunction, such as hypothyroidism and diabetes insipidus, can occur after transsphenoidal resection of these cysts. CLINICAL CASE: A 14-year-old male presented to the ED with acute onset of a severe headache, nausea and emesis. He denied recent vision changes, weight changes, temperature intolerance, diarrhea, constipation, skin changes, polyuria, or polydipsia. He reported starting puberty by 13 years of age. He was treated with Zofran, Tylenol, and Dexamethasone which led to headache resolution. His MRI showed a trans-sellar structure measuring 12 by 16 mm and demonstrating internal intrinsic T1 hyper-intensity, deep T2 hypo-intensity, and mildly thickened peripheral enhancement. The lesion abuts the undersurface of the optic chiasm and the stalk enhances normally. The neurohypophysis is not well identified. The optic nerves are unremarkable, and the optic chasm is slightly bowed superiorly. His initial labs were significant for: Na 136 mmol/L, K 4 mmol/L, TSH 1.15 uIU/mL, FT4 0.81 ng/dL, IGF-1 286 ng/mL, cortisol <1 ug/dL (drawn in the PM), FSH 6.23 mIU/mL, LH 2. 01 mIU/mL, PRL 7.8 ng/mL, testosterone 187 ng/dL. He was taken to surgery where a transsphenoidal resection with a mucosal graft for sellar reconstruction was completed. Pathology results showed evidence of a neurenteric cyst with glandular elements within the cyst wall. He was noted to have an increase in water intake and urine output post-operatively with intake of 6200 mL and output of 6768 mL over 24 hours (3.5 mL/kg/hr). His Na was 141 mmol/L with urine SG of 1. 002, and urine osmolality of 75 mosm/kg. He was discharged on a DDAVP dose of 0.2 mg tid. His thyroid function was reassuring post-op with a T4 of 8.4 ug/dL. He had a normal morning cortisol of 14.6 ug/dL. One month post-op, he required treatment with a DDAVP dose of 0.1 mg bid. The rest of his pituitary function appeared intact one month post-op with labs significant for LH 2.56 mIU/mL, FSH 5 mIU/mL, testosterone 261 ng/dL, PRL 7.8 ng/mL, TSH 2. 09 uIU/mL, and FT4 1 ng/dL. CONCLUSION: This case demonstrates that neurenteric cyst apoplexy can occur in teenagers who present with the acute onset of a severe headache with associated nausea and emesis. This case demonstrates the importance of thoroughly investigating the patient's pituitary function at baseline and post-operatively since pituitary deficiencies, such as DI, can occur. Presentation: No date and time listed