What is adrenal cortical carcinoma (ACC), and what are its CT and MRI features?
ACC is the most common primary malignant tumor of the adrenal gland in adults; it arises from the adrenal cortex but is rare. It occurs slightly more commonly in women than in men and usually arises in infants and children <5 years old and in adults during the fourth to fifth decades of life. About 55% are hyperfunctional, most often leading to Cushing’s syndrome, and are generally smaller in size than when nonhyperfunctional. Treatment generally involves surgical resection when feasible as well as chemotherapy and radiotherapy as needed.
On CT and MRI, a large (>5 cm) enhancing adrenal gland mass is typically seen, which is usually heterogeneous in attenuation and signal intensity. Microscopic lipid content may be visualized on out-of-phase T1-weighted images, and sometimes a small amount of macroscopic fat may be present. Additional findings that may be encountered include prominent peritumoral vascularity, calcification (in up to 30%), invasion of adjacent organs or tissues, venous extension, regional lymphadenopathy, and distant metastatic disease (most often to the liver, lungs, and bone marrow)