Successful long-term control of Cushing’s disease after partial resection of gigantic ACTH-secreting pituitary adenoma

Only 4-9% of patients with Cushing’s disease (CD) harbor pituitary macroadenomas. Clinical and biochemical features of macrocorticotropinomas are poorly understood. Some evidence exist that these tumors presents clinical features more similar to a non-functioning adenomas, being though defined silent corticotropinomas, rather than to ACTH-secreting adenomas. In this paper, we report a case of a 60-year old woman with a history of obesity, arterial hypertension and diabetes mellitus who presented with overt central hypothyroidism. Magnetic resonance imaging disclosed giant pituitary adenoma measuring 50 mm. Endocrinological evaluation confirmed CD: ACTH 50.3 pmol/L, urinary free-cortisol of 739 nmol/24h and cortisol of 639 nmol/L after 1 mg dexamethasone suppression test. Tumor mass was reduced by 50% using purely endoscopic transsphenoidal approach. Thirty-eight months after the partial resection, the patient had well controlled CD: ACTH 20.2 pmol/L, urinary free-cortisol of 238 nmol/24h, cortisol of 105 nmol/L after 1 mg dexamethasone suppression test. To the best of our knowledge, this is the largest ACTH-secreting adenoma ever reported. Our case suggests that tumor size does not necessarily correlate with aggressiveness of CD in patients with macrocorticotropinomas and that long-term control of CD may be achieved albeit incomplete surgical removal. Further studies are needed in order to determine the best treatment option for patients with macrocorticotropinomas.