MON-055 A Rare Case of a Macroadenoma Causing Cushing Syndrome in a Pediatric Patient

Abstract Background: Pediatric Cushing Syndrome, a rare diagnosis, is almost always caused by pituitary microadenomas less than 5 mm in children older than 6 years old. We report on a 9-year-old girl with a 2.3 cm pituitary macroadenoma, whose ACTH and urinary 24-hour free cortisol were the highest recorded at our institution. Clinical Case: A 9-year-old pre-pubertal female presented with six months of frontal headaches, rapid weight gain, and hirsutism. Two months prior she developed fatigue and proximal muscle weakness and pain. On physical exam, she had plethoric round facies with acne and hirsutism, dorsal fat pad, central adiposity, and violet colored abdominal striae. Her pubertal development was tanner stage 3 for breast and 2 for pubic hair. BMI was 95th percentile and height was 40th percentile, previously 75th and 50th percentile respectively one year prior. 24 hour urinary free cortisol was 40,650 mcg/day [normal:100 mcg/day]. A 48 hour high dose dexamethasone suppression test was done as it is the most accurate in pediatric patients over 40 kg, morning cortisol was 100 mcg/dL [normal: 5-20 mcg/dL], ACTH 868 pg/ml [normal: 9-57 pg/ml], 24 Urinary Free Cortisol was 15,878 mcg/day [normal: 100 mcg/day]. A MRI Pituitary/Sella revealed a 2.3 cm pituitary macroadenoma superiorly displacing and flattening the optic chiasm, invading into the right cavernous sinus. She was referred to Neurosurgery, who did a partial transphenoidal resection, pathology consistent with ACTH producing tumor. Post-operatively she developed central diabetes insipidus and adrenal insufficiency for which she received desmopressin and oral hydrocortisone respectively. Her laboratory values eight months since surgery show normalization of ACTH and cortisol levels. The patient’s general health has improved, headaches have resolved, strength has returned, and her hirsutism is reduced. Her BMI remains elevated at 88% but is declining and growth velocity is increasing back to her pre-disease level. Conclusion: Cushing Syndrome is exceedingly rare in pediatric aged patients and pituitary macroadenomas are atypical in this population.This is a unique case of an ACTH producing macroadenoma in a Pediatric patient, which has seldom been reported in the literature, and should be considered in patients with similar presenting symptoms.