Figure 2. CT images of adrenal pathologies presenting as adrenal incidentalomas. a,b,c: A patient with a benign (lipid-rich) adrenal adenoma with unenhanced attenuation value – 3 HU (a), early attenuation (60 seconds after i.v. contrast medium administration) 35 HU (b) and delayed attenuation (10 min post-contrast administration) 18 HU. ARW = 45% and RPW=49%. Absolute washout (APW) less than 60% is indeterminate. However, the low pre-contrast attenuation is suggestive of an adenoma. Relative washout (RPW) of 40% or higher is consistent with an adenoma; d,e,f: Biochemically and histologically proven pheochromocytoma with unenhanced attenuation of 49 HU (d), early attenuation 90 HU (e) and delayed attenuation 64 HU. ARW = 63% and RPW=29%. Absolute washout >60% is suggestive of an adenoma, however relative washout less than 40% and unenhanced attenuation >10 HU are indeterminate; g,h: A patient with a primary adrenocortical carcinoma characterized by heterogeneity an unenhanced attenuation value >10 HU (g) and inhomogeneous contrast medium uptake due to central areas of necrosis; i: Typical myelolipoma.