Marcia with my son they also did an ultra sound but the adrenals are hard to see on these.  He had MRI of the pituitary and CT scans of the adrenals.  Adrenal rests can occur in different parts of the body, as far as I can understand it, and please someone correct me if I am wrong, I know with boys adrenal rests in the testes are common. My son also tried dex and pred, he became extremely ill as he was running out of cortisol very quickly.  I read the Addison’s board and there are many people who really battle with the disease.  If your daughter clears cortisol quickly, you may still run into problems with taking the hydrocortisone as it will still clear quickly, with an adrenalectomy.  I appreciate though, that your daughter will not then suffer with the high androgen levels. I would make sure that you have explored every avenue first as you can not put back the adrenals.