A woman affected by Cushing's disease underwent bilateral adrenalectomy followed 
by radiotherapy of the hypothalamic-pituitary area when she was 18 years old. 
Thereafter, she used hydrocortisone acetate replacement therapy (35.5 mg divided 
into two daily doses). At the age of 26 years, the patient exhibited the 
clinical signs of the Nelson's syndrome, i.e. skin and gingival 
hyperpigmentation accompanied by amenorrhea, and elevated ACTH plasma levels 
(2,850 pg/ml, normal range 15-80 pg/ml). The magnetic resonance imaging (MRI) 
analysis of the sellar region evidenced a pituitary macroadenoma, measuring 14 x 
13 mm. The patient was initially treated with cyproheptadine hydrochloride (12 
mg/day) for 18 months. There was a partial improvement of the symptoms, with a 
reduction of the ACTH plasma levels to 112 pg/ml, but without any modification 
of the tumor mass. Due to sleepiness and weight gain, the cyproheptadine 
treatment was interrupted and substituted by a cabergoline (0.5 mg twice a week) 
therapy. Soon after cabergoline was applied an improvement of the clinical 
symptoms and signs was observed such as a regression of the tumor mass and the 
normalization of the ACTH plasma titers (38 pg/ml). Later, cabergoline was 
substituted by bromocriptine (7.5 mg/day) and the plasma levels of ACTH 
increased again (247 pg/ml), and headache and cutaneous hyperpigmentation were 
recorded. When cabergoline was reintroduced there was a clinical improvement and 
normalization of ACTH plasma levels (64 pg/ml). The MRI analysis of the sella 
region demonstrated a complete remission of the pituitary adenoma. The results 
obtained show for the first time that a long-term treatment with cabergoline 
also brings about a complete remission of Nelson's syndrome in the presence of a 
pituitary macroadenoma.