Presentation and Clinical Patterns of Bilateral Adrenal Lesions: A Retrospective Cohort Study

CONTEXT: The clinical relevance of etiologic concordance and temporal presentation in bilateral adrenal masses remains poorly defined, creating uncertainty in diagnostic evaluation and management. OBJECTIVE: To characterize the etiologic spectrum of bilateral adrenal masses, evaluate patterns by concordance and synchronicity, and identify predictors of discordance and malignant or pheochromocytoma contralateral lesions. DESIGN: Retrospective cohort study (2010-2025). SETTING: Tertiary referral center. PARTICIPANTS: Adults with bilateral adrenal masses. MAIN OUTCOME MEASURES: Etiology, concordance, synchronicity, interval to contralateral lesion, and factors associated with discordance and malignant or pheochromocytoma contralateral lesions. RESULTS: Among 1,035 patients (median age 59.6 years; 51% women), 85% had concordant and 15% discordant etiologies. Concordant cases were predominantly bilateral benign cortical lesions (76%), whereas discordant cases were heterogeneous (benign 35%, malignant 31%, indeterminate 34%). Presentation was synchronous in 84% and asynchronous in 16%, with a median interval of 45 months (IQR 15-87). Asynchronous disease was associated with higher discordance (23% vs 13%, P=0.001) and greater prevalence of malignant lesions (bilateral malignant: 17% vs 7%; discordant malignant: 8% vs 4%; overall P<0.001). Among asynchronous cases, shorter interval to contralateral lesion (<2 vs ≥5 years) was independently associated with malignant or pheochromocytoma etiology (adjusted OR 2.63, 95% CI 1.01-6.85), as was larger tumor size (adjusted OR 1.06 per mm, 95% CI 1.02-1.09). CONCLUSIONS: Most bilateral adrenal masses are benign and concordant; however, discordant or asynchronous disease identifies a higher-risk subgroup enriched for malignancy. Early contralateral lesion development and larger tumor size are key risk factors.