ODP304 Cyclic Cushing Disease: A Diagnostic Challenge

BACKGROUND: Cyclic Cushing syndrome is a clinical challenging diagnosis due to an unpredictable duration of periodic hypercortisolemia shifting with normocortisolemia periods. Only small proportion of such cases are due to a corticotroph pituitary adenoma with cyclic activity. Clinical case: 27-year-old after she stopped nursing her baby, she had no resumption of menses. She then developed mild headache and weight gain of 20kg throughout 3 months. She also developed facial hair, acne, easy bruising and striae. She was evaluated by a local physician where Cushing syndrome (CS) was suspected. Local testing showed the following results: UFC: 1117 and 1572 mcg/24h (<403mcg/24h), low dose DST of 595.8 nmol/l (<50nmol/l) and ACTH 60 pg/mL (10-100pg/mL). An MRI identified a 6 mm pituitary adenoma. The patient was sent to our pituitary clinic under the diagnosis of Cushing disease (CD). Upon examination at our institution, the patient reported asthenia, mood changes, depression and hirsutism. The physical examination revealed classical signs of CS. No other comorbidities were detected. A seven-hour 7mg dex infusion testwas performed (1), with basal cortisol of 187.5 nmol/l, early suppression of 12.6 nmol/l and late suppression of 27.5 nmol/l which is negative for hypercortisolism. As the high suspicion of CS, the patient was followed monthly with UFC and serum cortisol. During this normocortisolemia period the patient lost 10kg of weight, recovered its menses and coloration changes of striae. Laboratory follow up UFC of 67, 71 mcg/24h and serum cortisol of 124, 270, 103.4, 358.6 and 413 nmol/l ACTH 20, 21, 23, 28, 25 pg/mL. After 6 months of no clinical sign of hypercortisolism the patient reached to us as she noticed her striae changed, started gaining weight, lost menses and changed headache frequency. Laboratories revealed UFC was 754.6 mcg/24h and low dose DST was 751.1 nmol/l and ACTH of 70 pg/mL. We conducted another continuous 7mg dex infusion for seven hours with basal cortisol of 669.2 nmol/l, early suppression of 90.2 nmol/l (>50% suppression) and late suppression of 691.5 nmol/l which was compatible with CD. Additional testing was performed, with a 18F-NOTA-Octreotide and a full body CT that did not reveal an ectopic ACTH producing tumor neither an adrenal mass. Patient underwent a transsphenoidal surgery and reached remission of her hypercortisolism. CONCLUSION: CD may be difficult to be confirmed but also it is important to consider that some cases showed cyclic activity. As far as we could acknowledged, this is the first case showing a 6-month period of normocortisolemia in a cyclic ACTH-secreting pituitary adenoma. Bibliography Biemond P, de Jong FH, Lamberts SW. Continuous dexamethasone infusion for seven hours in patients with the Cushing syndrome. A superior differential diagnostic test. Ann Intern Med. 1990 May 15;112(10): 738–42. Presentation: No date and time listed