Adrenal nodules on CT are common findings often found incidentally or as part of a test done for another reason. Adrenal nodules can range from benign abnormalities which can be left alone to cancer and metastasis. The radiologist will look at the imaging features of the mass, and any prior studies to determine the diagnosis, appropriate testing and follow up.
It also matters if the patient is healthy without cancer or with cancer. Adrenal nodules found in patients with a cancer history can represent metastasis. One of the most important features is stability over the years. An old study demonstrating no change in the appearance is reassuring for a benign cause. If the nodules has been stable for 1 year or more, and there is no evidence of hormone secretion by the mass, then it is likely benign.
Masses smaller then 1 cm are often benign and usually need no follow up. Masses which contain fat will have low density on CT and will represent adenomas or myelolipoma which are benign. Other benign adrenal nodules can be cysts, bleeding into the gland or calcified are usually benign and can be left alone. In some cases, probably benign adrenal nodules can be follow up in 12 months with another CT.
Those nodules which are not clearly adenomas or are new and enlarging based on prior imaging will need a dedicated CT of the adrenals to further evaluate. The adrenal CT results can further guide management and follow up.
If patient has a cancer history, then an adrenal CT can be attempted to characterize. Biopsy or PET CT may be needed if the CT is inconclusive. A cancerous spread to the adrenal gland will often be hotter on PET scan then an adenoma. A PET scan basically provides a map of how active or metabolic tissues are in the body. The idea being that cancers will be very metabolically active while normal or benign abnormalities less so. A biopsy may be needed in cases where it is still unclear.
Masses larger then 4 cm are often resected. If patient has a cancer history, then a biopsy or PET scan may be needed for larger masses which are clearly not metastatic. For a cancer patient with spread to the adrenal gland, more systemic therapies will be needed rather then resection.