THU623 Leuprolide Treatment Of Mild Cortisol Secretion (MACS) Due To Primary Bilateral Macronodular Hyperplasia (PBMAH) Expressing Aberrant LH Receptors

Disclosure: L. Branchaud-Croisetière: None. M. St-Jean: Speaker; Self; Recordati rare disease, GlaxoSmithKline. Stock Owner; Self; Spruce bioscience. Cushing syndrome (CS) is caused by PBMAH in <2% of cases. Treatment is mostly surgical with unilateral or bilateral adrenalectomy, but in some cases, identification of aberrant receptors can allow the use of targeted medical therapies. Only a few cases of adrenal CS associated with an aberrant LH/hCG receptors that were treated with GnRH agonist were described. In December 2020, we saw a 72-year-old woman for bilateral adrenal nodules and an ACTH independent hypercortisolism. Her past medical history includes depression, insomnia, and osteoporosis with multiples fragility fractures. She was taking citalopram, calcium, vitamin D and alendronate was added in 2021. In the follow-up she developed dyslipidemia and hypertension. There were no sign of CS on physical examination. In 2020, a non-contrast thoracic scan was done and showed a right adrenal nodule of 3x1,4 cm and a left adrenal nodule of 3 x 2 cm both with densities < 10 HU and no atrophy of the adrenal limbs. In August 2021, a FDG PET scan showed an SUV of 3,4 on the right side and 3,7 on the left side. Morning cortisol after 1 mg DST (done twice) were 122 and 133 nmol/L (N <50). Aldosterone to renin ratio and 17-OHP were normal. In September 2020, a 4 mg IV dexamethasone suppression test was done and cortisol was 189 nmol/L at 9h am on day 2. Between 2020 and 2021, ACTH (3 values) were between 1,3-1,7 pmol/L (N 0-10 pmol/L) and DHEAS (3 values) between 1-1,6 (N 0,95-11,67 mol/L). 24h UFC (7 values) varied from 280,6 to 600,6 nmol/d (N 153-789 nmol/d). LNSC (8 values) were normal <2 to 3 nmol/L (N <5) except for one value at 6 nmol/L. In February 2022, systematic research for aberrant receptors was done. The cortisol have showed an ACTH-independent increased of 242% following 100 mcg IV of LHRH. There was also a significant ACTH-independent increase after 10 IU of vasopressin (+ 66%) and 10 mg of maxeran PO (+ 98%). There was no significant increase in cortisol after stimulation with glucagon 1mg IV and the upright posture test. We couldn’t obtain cortisol measures after stimulation with cortrosyn and the mixed-meal test because of issues with samples. Treatment with Leuprolide 3,75mg IM monthly was started in April 2022 and the dose was increased to 7,5 mg in August 2022 because of partial response observed initially. There was a response with an increase in ACTH from <1,1 to 2,6 pmol/L until December 2022. Since January 2023, ACTH (3 values) have decreased between 1,8-2 pmol/L. In January 2023, the morning cortisol after 1 mg DST was 104 nmol/L and 24h UFC were 161 and 306 nmol/d and two LNSC were <2 nmol/L. However, with the recent decrease in ACTH, we suspect an escape to Leuprolide. In summary, this is a rare case of MACS due to PBMAH expressing aberrant LH receptors with initial response to Leuprolide. We are waiting for the results of genetic testing. The patient could eventually benefit from a left unilateral adrenalectomy if escape from medical treatment is confirmed. Presentation: Thursday, June 15, 2023