Adrenal schwannomas and adrenal ganglioneuromas: our experience and CT characteristic-focused systematic review.

PURPOSE: The accuracy of computed tomography (CT) parameters in the preoperative diagnosis of benign adrenal lesions, such as adrenal schwannoma (AS) and adrenal ganglioneuroma (AG), has not been systematically studied. Hence, we aimed to analyze CT features of AS/AG to distinguish them from other lipid-poor, poor-washout adrenal masses. METHODS: Description of our AS/AG cohort, along with systematic review of literature for histopathologically confirmed AS/AG and available CT characteristics (providing unenhanced, early venous, and delayed venous phase attenuation). These were compared with our previously published cohort of other lipid-poor, poor-washout adrenal masses (n = 47). RESULTS: The cohort included AS (n = 30; literature:25, our center:5), AG (n = 27; literature:25, our center:2). AS and AG were similar, except AG patients were younger (28 vs. 49.5 years, p = 0.003). All AS and 92.5% of AG were nonsecretory. Progressive delayed enhancement (PDE) [relative percentage washout (RPW) < 0%] occurred in all AS and 70.4% of AG. Compared to other masses, AS were more often nonsecretory (100% vs. 68.1%, p < 0.001), cystic (71.4% vs. 10.6%, p < 0.001), calcified (52.6% vs. 10.6%, p = 0.001), and had lower RPW (-19.7% vs. 24.3%, p < 0.001). RPW achieved highest AUC (1.000), with 100% sensitivity and specificity at -1.5%. Similarly, AG were younger (28 vs. 42 years, p = 0.022), more often nonsecretory (92.5% vs. 68.1%, p = 0.020), and had lower RPW (-36.3% vs. 24.3%, p < 0.001; AUC:0.923) with 100% specificity and 70.4% sensitivity at -3.4%. CONCLUSION: PDE in a lipid-poor, poor-washout adrenal mass is specific for AS and AG and makes other common etiologies unlikely. External validation is required before widespread clinical integration.