SUN-190 Bilateral Pedal Edema as a Rare Presentation of Pediatric Cushing’s Syndrome

Abstract Disclosure: P. Gupta: None. E.Y. Choi: None. P.H. Nichols: None. Cushing’s Syndrome (CS) is a rare and serious chronic endocrinopathy with an overall incidence of 0.7-2.4 per million people per year. Cushing Disease (CD) is caused by an ACTH-producing pituitary adenoma leading to hypercortisolemia. A 16-year-old female presented with bilateral pedal edema without classic cushingoid features, an unusual presentation of this rare syndrome. The patient endorsed weight gain, bilateral pedal edema and menstrual irregularity for 6 months prior to presentation. Classic cushingoid features of dorsocervical fat pad, purple violaceous striae, moon facies, skin thinning, bruising, or muscle weakness were absent. Biochemical studies including serum electrolytes, serum albumin, and urine protein were normal and excluded nephrogenic causes of bilateral pedal edema. An evaluation for PCOS, non-classic CAH, prolactinoma, and other causes of hyperandrogenism was also normal which led to further consideration of Cushing’s Syndrome (CS). First-line testing revealed elevated 24-hour urinary free cortisol (151 ug/24 hr,normal range 6-42 ug/24 hr) and elevated midnight salivary cortisol (2.3 ug/dL,normal range <0.010 - 0.090 ug/dl). Low-dose dexamethasone (1 mg) suppression test showed suboptimal suppression of morning cortisol (9.5 ug/dL) from midnight serum cortisol of 11.2 ug/dL. High-dose dexamethasone (8 mg dose) suppression test showed suppression of cortisol to 1.4 ug/dL, consistent with CD. MRI brain with pituitary protocol showed 8 x 6 x 5 mm microadenoma in the left aspect of anterior pituitary gland. The patient underwent endoscopic transsphenoidal resection of pituitary microadenoma with immunohistochemistry positive for TBX19, ACTH, CK CAM 5.2 transcription factors and negative for SF1, PIT1, LH, FSH, GH, TSH & Prolactin, further confirming the diagnosis of ACTH-producing microadenoma causing Cushing’s Disease. Six months following surgical resection, the patient lost 31 lbs. and bilateral pedal edema resolved. This case highlights the unusual presentation of bilateral pedal edema in pediatric CS patients. Pediatric endocrinologists should consider the diagnosis of CS in the presence of unusual symptoms like bilateral pedal edema along with non-specific symptoms of weight gain and menstrual irregularity. Presentation: Sunday, July 13, 2025