Approach to an incidental adrenal mass

Adrenal masses may be identified in a patient where the significance is unknown; this is likely to occur more frequently with more widely available advanced diagnostic imaging. The approach to the identified mass may be unclear, in particular when the patient has presented with vague/lack of clinical signs compatible with a functional mass. The same dilemma exists in people; as a result guidelines have been developed. Adaptations of these guidelines based upon prevalence data in the dog and cat can be applied to our patients.

Adrenal masses are most likely to be identified using abdominal ultrasound in practice; however, they may also be detected using abdominal radiography, computed tomography (CT) scanning, and magnetic resonance imaging (MRI).

With abdominal ultrasound the left adrenal gland can be found craniomedial to the left kidney, ventrolateral to the aorta and between the origin of the craniomesenteric and left renal arteries, and is peanut-shaped. The right adrenal gland is craniomedial to the hilus of the right kidney, dorsal or dorsolateral to the vena cava and between the origin of the cranial mesenteric and right renal arteries, and is comma-shaped. Identification may be aided by the knowledge that the phrenicoabdominal vein crosses the mid-portion of both glands (see Figure 1 for an example of an incidental right-sided adrenal mass found on ultrasound) (Barthez et al, 1998).