Clinicians requesting imaging scans can now quantify incidental abnormalities, termed “incidentalomas,” according to a study published in BMJ.

Jack W. O’Sullivan, clinical researcher at the University of Oxford, and associates conducted an umbrella review of systematic reviews to report an evidence-based synopsis of the prevalence and outcomes of incidentalomas identified during imaging.

The investigators used data from observational studies that provided a frequency for incidentalomas, which are defined as abnormalities observed in asymptomatic, healthy patients or abnormalities in symptomatic patients that do not correlate with the patients’ symptoms or diagnoses.

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The measured frequencies of incidentalomas in patients with histories of malignancies were used in sensitivity analyses.

A total of 20 systematic reviews comprising 240 primary studies were used; frequencies of incidentalomas were identified from 15 reviews and outcomes were identified from 18 of the 20 reviews (13 provided both frequency and outcome information).

Substantial variation in incidentaloma prevalence was identified between imaging tests. For incidental pulmonary embolism in patients with and without cancer, a <5% prevalence was reported with chest computed tomography (CT) and whole-body positron emission tomography (PET) or PET/CT. However, more than one-third of cardiac magnetic resonance imaging (MRI), chest CT, and CT colonoscopy resulted in incidentalomas.

Spine and brain MRIs both resulted in 22% incidentaloma occurrence rates. The frequency of malignancies in incidentalomas ranged significantly between organs with the least found in the brain, parotid gland, and adrenal glands (all <5%). Malignancies in extra-colonic, prostatic, and colonic incidentalomas occurred between 10% and 20% of the time; malignancies in renal, thyroid, and ovarian incidentalomas occurred nearly 25% of the time, and brain incidentalomas had the most frequent malignancies (42%).

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“There is large variability across different imaging techniques both in the prevalence of incidentalomas and in the prevalence of malignancy for specific organs,” reported the authors. “This umbrella review will aid clinicians and patients [in weighing] the pros and cons of requesting imaging scans and will help with management decisions after an incidentaloma diagnosis.”


O’Sullivan JW, Muntinga T, Grigg S, Ioannidis JPA. Prevalence and outcomes of incidental imaging findings: umbrella review. BMJ. 2018;361:k2387