What are the cross sectional imaging features of metastatic disease to the adrenal glands?
Metastatic disease to the adrenal gland is the most common malignant tumor of the adrenal gland (occurring in up to 27% of patients with cancer at autopsy), and it most often occurs in the setting of lung cancer (most common), breast cancer, melanoma, gastrointestinal tract cancer, pancreatic cancer, and RCC. However, even in patients with known malignancy and an adrenal lesion, adrenal metastasis is less common than adrenal adenoma. CT, MRI, and FDG PET are commonly used for the detection and characterization of adrenal gland metastases in patients with known cancer.
On CT and MRI, the suspicion for adrenal metastatic disease is greater when the adrenal lesions are large (>4 to 5 cm in size), are multifocal and bilateral, are heterogeneous, have irregular margins, invade adjacent organs or tissues, grow over time or are new, or are seen in the presence of metastatic disease to other sites of the body. Specific diagnostic features of adrenal adenoma or other benign adrenal lesions will most often not be present on CT or MRI. On PET, adrenal nodule FDG uptake greater than that of liver is also suggestive of adrenal metastatic disease in a patient with known primary malignancy. When necessary, percutaneous biopsy is performed to distinguish between an adrenal metastatic disease and a benign adrenal lesion.