Clinical heterogeneity and imaging-driven genetic screening priorities in patients with radiologically suspected primary bilateral macronodular adrenal hyperplasia.

Objective: To investigate the clinical spectrum, ARMC5 mutation distribution, and metabolic/cardiovascular risks in patients with radiologically suspected primary bilateral macronodular adrenal hyperplasia (PBMAH). Design: Cross-sectional study. Methods: We analyzed clinical characteristics and germline ARMC5 mutations in patients meeting radiologic criteria for PBMAH (bilateral adrenal nodules ≥1 cm), excluding non-adrenocortical lesions or bilateral adenomas with adrenal atrophy. Results: The subgroup distribution among 485 patients with radiologically suspected PBMAH was as follows: nonfunctional adrenal tumors (NFAT, 30.1%), mild autonomous cortisol secretion (MACS, 41%), overt Cushing's syndrome (CS, 14.4%), primary aldosteronism (PA, 8.9%), and coexisting PA and MACS (PA + MACS, 5.6%). Imaging revealed a higher proportion of multiple confluent adrenal nodules in the MACS and CS groups compared to others (P < 0.05). Cortisol-related comorbidities (hypertension and diabetes) showed no statistically significant differences between MACS and NFAT. Germline ARMC5 testing in 62 unrelated patients identified seven novel pathogenic variants. Pathogenic mutations were detected only in MACS and CS groups, with no significant difference observed between them (P > 0.05). Multiple confluent nodules were present in all ARMC5-mutated patients (16/16) but in fewer ARMC5 wild-type patients (20/44), with high sensitivity and negative predictive value for the prediction of germline pathogenic mutations. Conclusion: No significant cortisol-related comorbidity differences were observed between radiologically suspected PBMAH patients with NFAT and MACS. Germline ARMC5 screening should prioritize patients with radiological findings of multiple confluent macronodules. Significance statement: Our work provides new insights into the management of primary bilateral macronodular adrenal hyperplasia (PBMAH): i) MACS and NFAT patients with radiologically suspected PBMAH (i.e., bilateral benign adrenal macronodules) may require equal clinical attention; ii) we identified seven novel ARMC5 pathogenic variants; iii) multiple confluent adrenal nodules on imaging demonstrate predictive value for ARMC5 pathogenic mutations, refining genetic screening criteria.