Size:
(1) typically >= 4.0 cm in diameter but may be smaller
(2) stable to rapidly enlarging (> 2.0 cm per year)
(3) usually solitary and unilateral
Shape: irregular with unclear margins
Imaging features of an adrenal carcinoma:
(1) heterogeneous texture with areas showing mixed densities
(2) attenuation (density) on unenhanced CT is usually > 25 Hounsfield units (almost all have a density > 10 HU)
(3) vascular
(4) washout of contrast material is < 50% at 10 minutes
(5) T2-weighted MRI images are hyperintense in relation to the liver
(6) necrosis and hemorrhage are common
(7) calcifications are common
It may be difficult to distinguish an adrenocortical carcinoma from a pheochromocytoma on imaging studies. The features favoring adenocarcinoma:
(1) hormonal activity
(2) irregular shape with unclear margins
(3) less cystic
(4) more calcifications
