Abstract 140: Pediatric macrocorticotropinoma: Do they differ from microcorticotropinoma?

Context: Cushing's disease (CD) due to macrocorticotropinoma (MC) in children and adolescents is a rare entity with limited information regarding its characteristics. Objective: To describe the clinical, biochemical, imaging, management, outcome and genetic characteristics of children and adolescents with CD due to MC (n = 32) and compare them with those of microcorticotropinoma (mc, n = 65) Design: Retrospective study (January 1997-January 2021) Setting: Single tertiary-care center Patients: Children/adolescents £ 20 years at the diagnosis of CD due to MC (maximum tumor diameter of >1 cm). Results: Nineteen girls and 13 boys with MC presented at a median (IQR) age of 14.5 (12.0-17.9) years. Patients with MC had higher body mass index-standard deviation score (BMI-SDS) (3.70 ± 2.60 vs 2.59 ± 2.01, p 0.04), more frequent neuro-ophthalmic symptoms (25% vs 9.2% p 0.04) and short stature (58.6% vs 34.4%, p 0.049) but less frequent livid striae (53.1% vs 78.1%, p 0.01), and hypokalemia (11.5% vs 36.2%, p 0.04) and lower cortisol (nmol/l) to corticotropin (pmol/l) ratio (41.20 vs. 55.74, p 0.05) than those with mc. The remission (58.6% vs 64.4% p 1.0) and relapse (52.9% vs 36.8% p 0.26) rates after first-line surgery and remission rate after radiotherapy (RT) were comparable between the two cohorts whereas time to remission after RT (27 vs 13 months, p 0.05) was longer in the MC group. A patient with MC had a pathogenic germ line variant in CDH23. Conclusion: In this large monocentric series of pediatric CD, frequent mass effect symptoms and short stature, higher BMI-SDS, less frequent livid striae and hypokalemia with lower effective cortisol secretion characterize the MC cohort. The outcomes of surgery and RT were similar between the groups except for a longer time to remission after RT in the MC cohort.