Cushing syndrome in a child due to pro-opiomelanocortin (POMC) secretion from a yolk sac tumor.

Context: Pituitary microadenomas and adrenal tumours are the most common causes for endogenous Cushing syndrome (CS) in children.

Case Description: We describe a two-year old girl with Cushing syndrome due to ectopic pro-opiomelanocortin (POMC) production from an abdominal yolk sac tumor. Cortisol concentrations were elevated but adrenocorticotropic hormone (ACTH) concentrations were equivocal.