Natural histories differ between unilateral, bilateral adrenal incidentalomas

Last Updated: 2015-07-28

By Will Boggs MD

NEW YORK (Reuters Health) - Bilateral adrenal incidentalomas are more likely to be associated with subclinical Cushing syndrome, whereas unilateral adrenal incidentalomas are more likely to be pheochromocytomas, according to a retrospective database analysis.

"The evaluation of unilateral incidentaloma has been very well studied over the last decade or more," Dr. Quan-Yang Duh, from the University of California, San Francisco, told Reuters Health by email. "However, we (the surgeons, endocrinologists, radiologists at our monthly conference) were less comfortable when we were confronted with bilateral incidentaloma (about 10-20% of the incidentalomas). Although we all had some gut feelings about what to do, we were not sure that we were doing the right things. That was the main reason for the study."

As many as 5% of patients undergoing abdominal cross-sectional imaging studies for unrelated reasons will have an incidentally discovered adrenal lesion that requires further evaluation.

Dr. Duh and colleagues investigated the characteristics and natural history of 135 patients with adrenal incidentalomas, 23 of whom had bilateral lesions.

Right-sided and left-sided lesions were similar in size and median density (by computed tomography Hounsfield units), according to the July 22 JAMA Surgery online report. The radiological descriptions of about three-quarters of the lesions were consistent with adenomas.

Just over a fifth (5/23) of patients with bilateral incidentalomas had subclinical Cushing syndrome, compared with only seven of 112 (6.3%) patients with unilateral incidentalomas.

In contrast, only one patient with bilateral incidentaloma had pheochromocytoma, compared with 22 patients (19.6%) with unilateral incidentaloma.

Two patients, both in the unilateral incidentaloma group, had adrenocortical carcinoma.

The sole patient with pheochromocytoma was the only bilateral incidentaloma patient to undergo resection (which was unilateral).

"The main way this paper influences what we do is by adjusting the 'pretest probabilities' of these conditions and helping us interpret the tests properly," Dr. Duh said. "It does not change what tests should be done, but does predict how likely the results may be positive."

"The work-up for bilateral adrenal incidentalomas is similar to that for unilateral incidentalomas," Dr. Duh concluded. "However, patients with bilateral incidentalomas are more likely to have subclinical Cushing's and less likely to have pheochromocytoma. This difference should be kept in mind when clinicians are evaluating these patients."

"Multidisciplinary conference to evaluate patients with incidentally discovered adrenal tumors is an efficient and effective way to help take care of these patients," Dr. Duh said.

"The evaluation of patients with bilateral adrenal incidentalomas is considerably more nuanced than the evaluation of patients with an isolated unilateral incidentaloma," wrote Dr. Linwah Yip and Dr. Sally E. Carty, from the University of Pittsburgh, Pennsylvania, in an accompanying commentary. "Surgery is not always indicated even with biochemical documentation of hormonal hypersecretion."

In an email, Dr. Carty told Reuters Health that one value of these findings is that nonoperative management of bilateral adrenal incidentalomas has a well-tolerated and benign course with follow-up of nearly five years. She added that the health care dollar could benefit greatly from this nonoperative approach, though the study does not address this directly.

Dr. Carty also emphasized the importance of making the diagnosis of subclinical Cushing syndrome, since undiagnosed subclinical Cushing syndrome can make a patient quite sick after adrenalectomy.

Dr. Peter Fuller, from the Hudson Institute of Medical Research's Centre for Endocrinology and Metabolism, Monash Medical Centre, Clayton, Victoria, Australia, told Reuters Health by email, "It is important to note that this is a tertiary referral service and all are getting presented at a multidisciplinary adrenal conference which is unusual for the routine adrenal incidentaloma; so the cohort probably has a degree of selection bias."

"That subclinical hypercortisolism was more common in the bilateral group is not something that I had given any thought to; it is new information, surprising not so much, but certainly argues for testing in this context," Dr. Fuller said. "That being said, they do not advocate a change to existing approaches/protocols."

This study was presented at the Pacific Coast Surgical Association annual meeting earlier this year.

The authors reported no disclosures.

SOURCE: http://bit.ly/1SKYyKz and http://bit.ly/1OMW3Xs

JAMA Surg 2015.