Cushing's syndrome in pediatric patients has been rarely reported and most of the cases are due to adrenal tumors. When the etiology is an ACTH-secreting pituitary adenoma, most often it is a microadenoma. We report on a 9 year-old girl with an ACTH-secreting macroadenoma, whose surgical removal through transsphenoidal approach was extremely difficult due to invasion of the cavernous sinus as well as adjacent structures. After two surgical approaches and stereotactic radiotherapy, she still suffers from the deleterious effects of hypercortisolism, especially marked osteoporosis with vertebral collapse, which interferes with her walking and causes excruciating pain. Two months after the radiotherapy, we still had doubts about the prognosis regarding the persistence of the hypercortisolism. From six months on, her general health started improving, she lost weight, the backache disappeared and her cortisol level returned to normal.