Etiology-, Sex-, and Tumor Size-Based Differences in Adrenocorticotropin-Dependent Cushing Syndrome

Objective: To examine demographic, clinical, and biochemical differences in patients with adrenocorticotropin (ACTH)-dependent Cushing syndrome (CS) based on etiology, sex, and tumor size. Methods: This was a single-center study of 211 patients with ACTH-dependent CS followed for 35 years. Patients were stratified into 3 groups based on etiology: Cushing disease (CD)/transsphenoidal surgery, Cushing disease/total bilateral adrenalectomy (CD/TBA), and ectopic ACTH secretion (EAS). Patients were also stratified based on sex and tumor size (nonvisualized, microadenoma, and macroadenoma). Results: CD was the commonest cause of ACTH-dependent CS (190; 90%). Most patients presented in the third decade (median age, 29 years). Clinical features, cortisol, and ACTH were significantly greater in the EAS group. The CD/TBA group had more nonvisualized tumors (22% vs 8%; P = .000) and smaller tumor size (4 vs 6 mm; P = .001) compared with the CD/transsphenoidal surgery group. There was female predominance in CD (2.06:1) and male predominance in EAS (2:1). Men had shorter duration of symptoms (2 years; P = .014), were younger (23 years; P = .001), had lower body mass index (25.1 kg/m2; P = .000), and had more severe disease (low bone mineral density, hypokalemia). Macroadenomas were frequent (46; 24.2%), and ACTH correlated with tumor size in CD (r = 0.226; P = .005). Conclusion: Our cohort presented at an earlier age than the Western population with a distinct, but slightly lower, female predilection. Patients with CD undergoing TBA had frequent negative imaging. Men had a clinical profile suggesting aggressive disease. Microadenoma and macroadenoma were difficult to distinguish on a clinicobiochemical basis.