The Lateralizing Asymmetry of Incidentally Discovered Adrenal Adenomas

Presentation Number: SUN 394
Date of Presentation: April 2nd, 2017

Meng Hao*1, Diana M Lopez1, Miguel Angel Luque-Fernandez2, Kathryn Cote3, Molly Connors3, Jessica Newfield3 and Anand Vaidya4
1Harvard Medical School, Boston, MA, 2Harvard School of Public Health, Boston, MA, 3Brigham and Women's Hospital, 4Brigham and Women's Hospital, Harvard Medical School, Boston, MA


Context: Incidentally discovered adrenal adenomas are common. It is presumed that the incidence of adrenal adenomas is symmetric between the left and right adrenal gland; however, anecdotal observations suggest a potential lateralizing asymmetry.

Objective: To investigate whether the incidental discovery of adrenal adenomas is symmetric or asymmetric and how this might impact patient care.

Methods: We conducted cross-sectional and longitudinal studies to assess the laterality of incidentally discovered adrenocortical adenomas. Study participants were selected from patients who underwent abdominal CT or MRI at our institution. We identified 1,700 consecutive patients with incidentally discovered adrenal masses and manually reviewed medical records to confirm the presence of an adrenal adenoma. We excluded 324 participants who were <18 years old, had a non-benign appearing adrenal mass, or had insufficient information to attain a final sample size of 1,376. We recorded the size and location of each adenoma, as well as co-morbidities at the time of imaging and in longitudinal follow-up. Analyses were conducted to assess differences in the prevalence of left, right, and bilateral tumors and the association with prevalent and incident outcomes using adjusted logistic regression.

Results: Left-sided adenomas were discovered in 65% (894/1376) of participants, right-sided in 21% (295/1376), and bilateral in 14% (187/1376), P<0.0001. Among unilateral adenomas, 75% (894/1189) were left-sided (P<0.0001). Although this left-sided lateralizing asymmetry diminished with larger tumor size, left-sided adenomas remained significantly more prevalent in each size category <1cm = 87%; 1-1.9 cm = 74%, 2-2.9 cm = 72%; ≥3 cm = 56% (P<0.0001 for each size category). Among those with bilateral adrenal adenomas, the left-sided tumor was significantly larger than the right-sided tumor in 61% of participants (P<0.001), with the left adenoma on average 9.9 mm larger in size than the right (P<0.0001). There were no significant differences in demographics, autonomous hormone secretion, or prevalence or incidence of cardiometabolic diseases between those with left vs. right-sided adenomas during 5.10 (SD=4.2) years of follow-up.

Conclusions: Incidentally discovered adrenal adenomas are 3 times more likely to be identified on the left adrenal than the right. Molecular susceptibilities that may result in asymmetric pathogenesis of adrenal adenomas warrant further investigation. Alternatively, these findings may highlight a detection bias due to the location and configuration of the right adrenal, which may preclude detection of tumors until they are substantially larger. This potential bias may result in preferential over-evaluation of patients with left-sided adenomas, and under-evaluation of patients with right-sided adenomas, as well as unreliable recognition of bilateral disease.


Nothing to Disclose: MH, DML, MAL, KC, MC, JN, AV