Adrenal cysts less than 10cm can be safely observed.

Abstract

Adrenal cysts are rare and appropriate management is unclear due to a lack of data on their natural history. Understanding adrenal cyst growth patterns would assist in clinical management. This single-institution study included all adult patients diagnosed with simple adrenal cysts between 2004 and 2021. Baseline characteristics and outcomes of those who underwent resection (ADX) or observation (OBS) were compared using the chi-squared test, student's t-test, and Wilcoxon rank-sum test. Growth curves and sensitivity analysis were plotted for all patients who had follow-up imaging. We identified 77 patients with imaging-confirmed adrenal cysts. The majority were female (75.3%) and more than half were white (55.8%). One-third of patients underwent ADX, and the remaining were observed. ADX patients were younger (median age [IQR]: 55.5y [45.0-68.2y] vs. 44.2y [38.7-55.0y], p=0.01) and more likely to be Hispanic (12% vs. 0%, p=0.05). ADX patients presented with larger cysts (5.6 vs. 2.6cm, p=0.002). The median time from diagnosis to last follow-up was 1.1y for ADX and 4.1y for OBS. Average growth for OBS was 0.3cm/y, while average growth for ADX was 3.9cm/y. In ADX patients, cysts >10cm grew significantly faster than cysts <10cm (median growth rate 13.2cm/y vs. 0.3cm/y, p<0.05). There was no adrenal malignancy diagnosis, hyperfunctionality, or observation-related complications (e.g., rupture). While size >4-6cm has guided surgical referral for solid adrenal masses, this study demonstrates a size threshold of 10cm, below which asymptomatic, simple adrenal cysts can safely be observed.