Outcomes and predictors of malignancy in radiologically non-adenomatous adrenal lesions: a retrospective study

Aims: To compare the clinical, radiological, functional, and pathological characteristics of radiologically diagnosed adrenal adenomas versus non-adenomatous lesions and to identify predictors of malignancy and clinical significance among the nonadenomatous group. Methods: This retrospective study included 63 adult patients who underwent adrenalectomy between January 2015 and December 2024. Patients were classified based on preoperative computed tomography (CT) and/or magnetic resonance imaging (MRI) reports as having either radiologically suspected adrenal adenoma or non-adenomatous lesions. Clinical features, comorbidities, hormonal function, imaging characteristics, and histopathological outcomes were compared between the two groups. Logistic regression analysis was performed within the non-adenomatous group to identify independent predictors of malignancy and clinical relevance. ROC curve analysis was used to assess the diagnostic utility of tumor size. Results: Of the 63 patients, 29 (46.0%) were classified as adrenal adenomas and 34 (54.0%) as non-adenomatous lesions. Tumor size was significantly smaller in the adenoma group (mean 27.1±6.8 mm vs. 48.5±13.7 mm, p<0.001). Functional tumors were more prevalent in the adenoma group (93.1% vs. 41.2%, p<0.001). Malignancy (adrenocortical carcinoma and metastasis) was observed exclusively in the non-adenomatous group. Within this group, functional lesions were independently associated with malignancy (p=0.019, OR=8.95). ROC analysis showed moderate diagnostic value of tumor size for predicting malignancy (AUC=0.648, 95% CI: 0.372–0.924). Histopathological confirmation showed perfect concordance in the adenoma group (positive predictive value 100%). The adenoma group had higher rates of hypertension (p=0.013) and coronary artery disease (p=0.012). Conclusion: Radiologically non-adenomatous adrenal lesions are more likely to be malignant than radiologically diagnosed adenomas. Tumor size and functional status can aid in malignancy prediction within this subgroup. Radiologic classification offers high specificity, particularly for adenomas, and may guide preoperative risk stratification.