I just read a very good article in the NY Times about a patient found to have the classic incidentaloma, a small mass in the adrenal gland. This is estimated to be seen in 4% of abdominal CT scans, and is rarely serious but typically leads to recommendations for additional testing and follow up CT scans to assure that it is not either a metastatic cancer from another area or a hormone secreting tumor of the adrenal gland itself. It is so common that the NIH has a formal recommendation article to guide physicians on how to manage a small adrenal mass found on imaging modalities, what they refer to as adrenal incidentaloma, and even have an acronym “AI.”
The term incidentaloma is a tongue-in-cheek to denote an incidental finding on an imaging test. –oma is the suffix used in the name of any tumor or enlargement. Examples are lipoma, condyloma, meningioma, teratoma, and dozens of others. The root of the term obviously refers to the fact that it was an incidental finding on a test looking for something else altogether.
Classic incidentalomas include:
- Tiny solitary pulmonary nodules: Commonly on chest x-ray or chest CT scan a small pulmonary nodule is seen. Most times these are the result of a prior fungal infection or previous inflammation, but often require follow up imaging.
- Small ovarian cysts seen on pelvic ultrasound. The ovaries of women of child bearing age form an ovulatory cyst each month, and commonly these normal cysts, or other small cysts of questionable importance are noted on pelvic ultrasounds done for evaluation of uterine fibroids, evaluation of abnormal bleeding, or other concerns where ovarian cyst or cancer is not the primary concern. Follow up ultrasounds, occasional surgery, and lots of emotional angst are the most common outcomes.
- Renal Cysts: Abdominal CT scans often show “lesions” in the kidney that require further evaluation to determine if they are simple renal cysts or possibly solid tumors. They usually are cysts, but are common incidental findings on CT scans done to look for kidney stones, diverticulitis, or other problems. Again additional evaluation with ultrasound and sometimes monitoring over time or even biopsy are done to further evaluate these incidentalomas.
- Lab test abnormalities, though not referred to as incidentalomas are other common incidental findings that often lead to a cascade of follow up testing. The most common example in my practice is minor elevation of liver enzymes called transaminases, or liver function tests. When abnormal these are usually repeated along with testing for viral hepatitis C and B. If they remain abnormal liver imaging, sometimes liver biopsy are often done. The usual outcome is a diagnosis of fatty liver, with advice to stop drinking alcohol, and lose weight. This is advice that could have been given without even knowing the liver enzymes were elevated.
Overall the whole incidentaloma problem is just one example of the real cost of ordering tests, especially tests like CT scans and MRIs that are so sensitive that they often find insignificant minor abnormalities or normal variants that lead to yet more expensive and sometimes invasive evaluation.