In human medicine, incidental adrenal gland masses are defined as adrenal gland masses that are incidentally identified during diagnostic imaging in patients without prior evidence of adrenal gland disease.1 These masses can be benign (eg, cortical adenomas, granulomas, cysts, or hyperplastic tissue) or malignant (eg, cortical carcinomas, pheochromocytomas, or metastatic masses).2,3 Incidental adrenal gland masses have also been reported in veterinary patients. A recent report4 indicated a 4% prevalence of incidental adrenal gland masses in dogs undergoing abdominal ultrasonography. That study found that dogs with an incidental adrenal gland mass were significantly older (median age, 11.25 years; range, 3.5 to 16.9 years) and heavier (median body weight, 21 kg [46.2 lb]; range, 2 to 56 kg [4.4 to 123.2 lb]), compared with the control population (median age, 9.5 years; range, 2 months to 19.2 years; median body weight, 14 kg [30.8 lb]; range, 1 to 71 kg [2.2 to 156.2 lb]).4
In human medicine, postmortem diagnosis of incidental adrenal gland masses has been reported in 2.3% of patients,5 and incidental adrenal gland masses have been identified in 1% to 10% of human patients on the basis of results of CT and magnetic resonance imaging.6–9 The prevalence of adrenal gland masses increased with age from < 1% in young adults, to 3% at 50 years of age, and up to 15% in patients > 70 years old.6,10 Another study11 evaluated the prevalence of incidental adrenal gland masses in routine clinical practice in the Irish adult population. In that study, incidental adrenal gland masses were detected in 0.98% of patients during abdominal CT and in 0.81% of patients during CT of the thorax.
Abdominal CT is becoming increasingly common in veterinary medicine. In our practice, we have observed anecdotally that adrenal gland masses are often diagnosed incidentally in dogs undergoing abdominal CT. In human patients, CT has been reported to be a superior modality for the diagnosis of adrenal gland masses, compared with abdominal ultrasonography.12 Currently, there is no comparable study in veterinary medicine. As such, the purposes of the study reported here were to determine the prevalence of incidental adrenal gland masses in dogs undergoing routine diagnostic abdominal CT, to describe the clinical characteristics of affected dogs, and to evaluate risk factors for the diagnosis of incidental adrenal gland masses in this patient population. We also hoped to evaluate outcome for patients with various types of incidental adrenal gland masses. We hypothesized that the prevalence of incidental adrenal gland masses in dogs undergoing CT would be higher than that previously reported for dogs undergoing abdominal ultrasonography4 and that incidental adrenal gland masses would be more common in older dogs.
This manuscript represents a portion of the work completed for the University of Florida Merial Veterinary Scholars Program and completion of VEM 5991: Individualized Investigation at the University of Florida College of Veterinary Medicine.
Presented as a poster at the 15th Annual Merial–National Institutes of Health Veterinary Scholars Symposium, Ithaca, NY, August 2014, and at the American College of Veterinary Surgeons Surgery Summit, Nashville, Tenn, October 2015.
The authors thank Blanca Carbia for technical assistance.
JMP, version 9.0.2, SAS Institute Inc, Cary, NC.
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