An unusual presentation of pediatric Cushing disease: recurrent corticotropinoma of the posterior pituitary lobe.

Cushing's syndrome (CS) is rare in childhood and adolescence and its diagnosis and work up are often challenging. We report the case of a 15-year-old girl with a recurrent corticotrophin (ACTH)-secreting adenoma, located in the posterior lobe of the pituitary gland. At the age of 11, she presented with classic CS symptoms; biochemical investigation was compatible with ACTH-dependent Cushing disease, although pituitary gland imaging did not show any tumor. Following transsphenoidal surgery (TSS), histopathological analysis identified an ACTH-secreting pituitary microadenoma arising from the posterior gland. The patient went into remission but 4 years later she presented with recurrent CS; this time, pituitary gland imaging showed a microadenoma located in the posterior lobe, which was resected after TSS. Posterior lobe pituitary adenomas are very rare and often hard to diagnose and treat; this is the first case of such a tumor causing recurrent Cushing's disease in a child.