Incidental Adrenal Nodules and Growth Rates: A Single Centre Retrospective Cohort Study.

Area of Science:

• Radiology
• Endocrinology
• Oncology

Background:

• Incidental adrenal nodules are frequently detected via computed tomography (CT).
• Current guidelines recommend one-year follow-up imaging, but its utility for malignant lesions is uncertain.
• Investigating adrenal nodule growth rates is crucial for refining follow-up protocols.

Purpose of the Study:

• To compare the growth rates of incidental adrenal nodules.
• To determine if current follow-up imaging guidelines are appropriate for adrenal nodules.
• To differentiate growth patterns between benign and malignant adrenal lesions.

Main Methods:

• Retrospective cohort study at Te Toka Tumai Auckland, New Zealand.
• Analysis of CT adrenal examinations from Jan 2010 to Dec 2015.
• Calculation and comparison of annual nodule growth rates for benign and malignant lesions.

Main Results:

• 75 adrenal nodules in 66 patients were analyzed.
• The single malignant nodule showed rapid growth (13 mm/39 days).
• Most benign nodules (95%) exhibited slow growth (-2 to +2 mm/year), with many remaining stable or decreasing in size.

Conclusions:

• Malignant adrenal lesions grow substantially faster than benign ones.
• A one-year follow-up interval may be insufficient for detecting rapidly growing malignant nodules.
• Adrenal nodule follow-up should incorporate baseline malignancy risk and observed growth rates.