OR18-06 A Global Approach to the Long-Term Follow-Up of 17 Families Affected by Bilateral Macronodular Adrenal Disease

Abstract Disclosure: H.L. Charchar: None. G.A. Alencar: None. B.M. Mariani: None. A.W. Kuhn: None. L. Bouys: None. P. Vaduva: None. M.Y. Nishi: None. F.L. Ledesma: None. M.Q. Almeida: None. V. Srougi: None. F.Y. Tanno: None. J.L. Chambô: None. A. Latronico: None. M.A. Pereira: None. J. Bertherat: None. B.B. Mendonca: None. M.C. Fragoso: None. Context: Bilateral macronodular adrenocortical disease (BMAD) is a rare and often underdiagnosed cause of adrenal Cushing’s syndrome (CS), presenting a spectrum of manifestations ranging from mild autonomous cortisol secretion (MACS) to overt CS. ARMC5 and KDM1A are the most important and frequent genes associated with BMAD-families, however,long-term follow-up of affected patients remain scarce. Objective: This retrospective study analyzed clinical-hormonal variability, genetic profiles, treatment modalities, and outcomes in 17 families and nine sporadic cases of BMAD over 8 to 410 months at a Brazilian tertiary center. Methods: A total of 250 individuals (50 index cases [IC] and 200 relatives [R]) were included. Clinical, hormonal, and imaging data, along with histological and genetic analyses of ARMC5 and KDM1A, were evaluated. Results: Among 250 individuals, 104 (26 IC and 78 R) carried germline pathogenic/likely pathogenic ARMC5 variants. No KDM1A (likely) pathogenic variants were identified in ARMC5-wild-type patients. ARMC5-positive index-cases exhibited severe clinical manifestations, evidenced by elevated cortisol levels (urinary, salivary, and post-dexamethasone suppression test) and reduced ACTH and DHEAS levels (p = 0.005, p = 0.042, p = 0.005, p = 0.041, and p = 0.007, respectively). ICs had larger adrenal nodules (p < 0.0001). Adrenal-sparing surgery achieved 100% remission, contrasting with a 40% remission rate for unilateral adrenalectomy. Central nervous system meningiomas were observed in BMAD-patients independently to ARMC5 status. Interestingly, malignant neoplasms were notably prevalent among ARMC5-altered individuals. Conclusion: A proposed management flowchart emphasizes genetic screening and the monitoring to mitigate the adrenal insufficiency period, MACS recurrence, and tumor risks development, underscoring the need for tailored therapeutic strategies in BMAD, depending on genetic alterations / ARMC5 status. Presentation: Sunday, July 13, 2025