Characterization of Unilateral Adrenal Incidentalomas: Hormonal Analysis, Computed Tomography, and Magnetic Resonance Imaging Correlation

TL;DR

This study examines adrenal tumors found by chance, comparing their hormonal activity and imaging features to distinguish benign from malignant cases.

Contribution

The study provides a detailed analysis of radiological and hormonal features of adrenal incidentalomas to improve diagnostic accuracy.

Findings

Non-functioning adenomas were the most common diagnosis, found in 80.4% of patients.

Cortisol-secreting adenomas were larger, more lipid-poor, and associated with higher rates of contralateral atrophy and hepatic steatosis.

Adrenocortical carcinomas were significantly larger and had higher CT density compared to lipid-poor adenomas.

Abstract

Introduction: Adrenal incidentalomas are adrenal masses detected on imaging performed for reasons other than suspected adrenal disease. Although most adrenal incidentalomas are nonfunctioning adenomas, some require treatment, particularly hormonally active or malignant lesions.

Objective: The purpose of this study was to analyze the clinico-hormonal and radiological characteristics of adrenal incidentalomas, to determine radiological features predictive of malignancy, and to compare nonfunctioning and cortisol-secreting adenomas in terms of radiological features.

Methods: This study involved 153 adult patients diagnosed with adrenal incidentaloma between 2015 and 2023. Clinical, hormonal, and imaging data were collected for all participants.

Results: The mean age of patients was 55 ± 13 years. Autonomous cortisol secretion was the most common hormonal activity, observed in 17% of cases, while 73.85% of patients had non-functional tumors. The most frequent diagnosis was adenoma, identified in 80.4% of patients. Adrenocortical carcinoma and pheochromocytoma were each diagnosed in 3.9% of patients. The mean size was significantly greater in adrenocortical carcinoma cases than in lipid-poor adenomas (61 ± 27.07 mm vs. 26.97 ± 11.85 mm; p = 0.027). The mean non-contrast CT density of adrenocortical carcinoma was 29.7 Hounsfield units, with a range of 18 to 41. Furthermore, cortisol-secreting adenomas were significantly larger than non-secreting adenomas and were more often lipid-poor. Contralateral adrenal atrophy and hepatic steatosis were significantly more prevalent in cortisol-secreting adenomas compared to non-secreting adenomas: (26.1% [n = 6] vs. 1.1% [n = 1]; p < 10⁻³) and (47.8% [n = 11] vs. 18.1% [n = 17]; p = 0.003), respectively.

Conclusions: We examined the clinical, radiological, and hormonal profiles of patients with adrenal incidentalomas, finding results consistent with existing literature. The main etiology in our series was a non-functioning adrenal adenoma. Autonomous cortisol secretion is the most prevalent hormonal activity. Imaging played a key role not only in distinguishing benign from malignant lesions but also in identifying features suggestive of cortisol secretion.