The term “incidental,” when used in a medical context, refers to something discovered completely by chance during a diagnostic procedure or screening test ordered for a different reason. This unexpected finding, often called an incidental finding, can sometimes cause anxiety for the patient because its significance is not immediately clear. These discoveries are becoming increasingly common due to the sophistication of modern medical imaging technologies. Understanding what an incidental finding is and how it is managed is an important part of navigating modern healthcare.
Defining Incidental Findings
An incidental finding is an abnormality or lesion that is not related to the symptoms or condition that prompted the original medical test. For example, a patient undergoing a computed tomography (CT) scan for severe back pain might unexpectedly be found to have a small nodule on their lung. The term “incidentaloma” is a commonly used term specifically for an incidentally discovered mass or tumor, most famously associated with the adrenal gland.
The rise in the use of advanced cross-sectional imaging, such as CT, magnetic resonance imaging (MRI), and ultrasound, has directly correlated with the increased detection of these findings. These high-resolution scans allow doctors to visualize the human body in greater detail, revealing subtle deviations from the norm. While many incidental findings represent benign or harmless conditions, their presence forces clinicians to assess their potential importance. This creates a dilemma because the finding was not what the doctor was initially looking for, meaning its clinical relevance is uncertain.
Common Locations and Examples
Incidental findings can occur in almost any part of the body, but certain organs are more frequently involved due to the common use of imaging in those areas. For instance, CT scans of the chest frequently lead to the discovery of small pulmonary nodules, which are small masses in the lung tissue. A study found that incidental abnormalities occurred in approximately 45% of patients undergoing chest CT.
Other common areas include the endocrine glands and abdominal organs. Small growths on the adrenal gland, often referred to as adrenal incidentalomas, are found in 0.6% to 1.3% of abdominal CT scans. Thyroid nodules are routinely found on neck imaging performed for other reasons, and small cysts or lesions are often seen in the liver and kidneys. While the prevalence of incidental findings is high, the percentage that turns out to be malignant is generally low, often less than 5% for findings in the adrenal gland or brain.
Medical Evaluation and Decision Making
Once an incidental finding is reported, a structured medical evaluation is necessary to determine the appropriate course of action, which is a process known as risk stratification. The doctor must assess the likelihood of the finding representing a serious condition, such as malignancy. This assessment considers factors like the finding’s size, its imaging characteristics (such as density or shape), and the patient’s medical history. Professional organizations, like the American College of Radiology, have developed evidence-based guidelines to help standardize the management of specific incidentalomas.
Based on this assessment, there are generally three possible management pathways. The finding may be dismissed if its characteristics strongly suggest it is benign and clinically insignificant, such as a simple cyst. The second pathway is active monitoring or surveillance, which involves repeat imaging—often in three to twelve months—to check for any changes in size or appearance. Finally, if the finding has suspicious features or is large, an intervention may be recommended, such as a biopsy or surgical removal, to definitively determine its nature.
A significant consideration in this process is the risk of “overdiagnosis,” which occurs when a condition is found that would never have caused symptoms or harm during the patient’s lifetime if left undiscovered. Pursuing an investigation of a likely benign finding carries its own risks, including patient anxiety, exposure to radiation from additional scans, and potential complications from invasive procedures like biopsies. Therefore, the decision to pursue further investigation requires a careful risk-benefit analysis, emphasizing shared decision-making between the clinician and the patient.