Table 1.

Imaging Characteristics of Benign Versus Malignant Adrenal Mass

Characteristic	Likely benign	Suspicious for malignancy
Size	Small (<4 cm)	Large (>4 cm)
Shape	Round or oval	Irregular
Margins	Smooth	Irregular
Texture	Homogenous	Heterogenous
Calcifications/Necrosis/Hemorrhage	Rare	Common
Growth	Slow	Rapid
Density of non-contrast CT	<10 HU	>10 HU
Contrast washout on CT protocol at 10–15 minutes	Absolute > 60% Relative > 40%	Absolute < 60% Relative < 40%
MRI chemical shift	Yes	No
FDG-PET	Non-avid	Avid

Abbreviations: CT = computed tomography; FDG-PET = fluorodeoxyglucose positron emission tomography; HU = Hounsfield units; MRI = magnetic resonance imaging.

Modified from Vaidya A. Endocrine Practice. 2019; 25(2):178–192.