Incidental imaging finding

In medical or research imaging, an incidental imaging finding (also called an incidentaloma) is an unanticipated finding which is not related to the original diagnostic inquiry. As with other types of incidental medical findings, they may represent a diagnostic, ethical, and philosophical dilemma because their significance is unclear. While some coincidental findings may lead to beneficial diagnoses, others may lead to overdiagnosis that results in unnecessary testing and treatment, sometimes called the "cascade effect".^[1]

Incidental findings are common in imaging. For instance, around 1 in every 3 cardiac

As the use of medical imaging increases, the number of incidental findings also increases.^[citation needed]

Adrenal

Incidental adrenal masses on imaging are common (0.6 to 1.3% of all abdominal CT). Differential diagnosis include

The first considerations are size and radiographic appearance of the mass. Suspicious adrenal masses or those ≥4 cm are recommended for complete removal by adrenalectomy. Masses <4 cm may also be recommended for removal if they are found to be hormonally active, but are otherwise recommended for observation.[5] All adrenal masses should receive hormonal evaluation. Hormonal evaluation includes:^[6]

• 1-mg overnight dexamethasone suppression test
• 24-hour urinary specimen for measurement of fractionated
  catecholamines
• Blood plasma aldosterone concentration and plasma renin activity, if hypertension is present

On CT scan, benign

Incidental thyroid masses may be found in 9% of patients undergoing bilateral carotid duplex ultrasonography.^[12]

Some experts

Most renal cell carcinomas are now found incidentally.^[19] Tumors less than 3 cm in diameter less frequently have aggressive histology.^[20]

A CT scan is the first choice modality for workup of solid masses in the kidneys. Nevertheless, hemorrhagic cysts can resemble renal cell carcinomas on CT, but they are easily distinguished with Doppler ultrasonography (Doppler US). In renal cell carcinomas, Doppler US often shows vessels with high velocities caused by neovascularization and arteriovenous shunting. Some renal cell carcinomas are hypovascular and not distinguishable with Doppler US. Therefore, renal tumors without a Doppler signal, which are not obvious simple cysts on US and CT, should be further investigated with contrast-enhanced ultrasound, as this is more sensitive than both Doppler US and CT for the detection of hypovascular tumors.^[21]

Spinal

The increasing use of MRI, often during diagnostic work-up for back or lower extremity pain, has led to a significant increase in the number of incidental findings that are most often clinically inconsequential. The most common include:^[22]

• vertebral hemangioma
• fibrolipoma (a lipoma with fibrous areas)
• Tarlov cyst

Sometimes normally asymptomatic findings can present with symptoms and these cases when identified cannot then be considered as incidentalomas.^{[citation needed]}

Criticism

The concept of the "incidentaloma" has been criticized, as such lesions do not have much in common other than the history of an incidental identification and the assumption that they are clinically inert. It has been proposed just to say that such lesions have been "incidentally found."^[23] The underlying pathology shows no unifying histological concept.^{[citation needed]}

References