Prevalence of venous extension in malignant adrenal neoplasia: beyond primary tumors and identification of a novel imaging sign.

objectiveTo assess the prevalence of adrenal vein involvement in primary and metastatic adrenal lesions and to determine if morphological changes in tumor shape precede venous extension. MATERIALS AND

methodsThis retrospective, single-center observational study evaluated 102 patients: 28 adrenal cortical carcinoma (ACC) patients, and 74 non-ACC cancer patients that presented adrenal metastasis (82 metastatic adrenal lesions). Two readers reviewed cross-sectional imaging to assess tumor size, laterality, venous invasion, and the presence of the "edge sign." Surgical and histopathological confirmation was the reference standard for ACCs, while for metastases, sequential imaging or PET-CT results showing hypermetabolism were used in 70.7% of cases and histopathology in 29.3% of cases.

resultsOf the 28 ACC patients, 82.1% were female, with balanced laterality. Metastases primarily originated from the lung (24.4%), colorectal (13.4%), and breast (12.2%) cancers and had a left-sided dominance (61.7%). Venous extension was present in 14.6% of metastases and 21.4% of ACCs, a non-significant difference (p = 0.40). The "edge sign" was more frequently observed in metastatic lesions than in ACCs, 26.8 × 17.8%, although this difference has not reached statistical significance (p = 0.34). In multivariate analysis, both mean size and the "edge sign" were independent predictors of adrenal and renal vein extension. Interobserver agreement was almost perfect for venous extension (κ = 0.9256) and substantial for the edge sign (κ = 0.7844).

conclusionVenous extension was less prevalent in metastatic adrenal lesions compared to ACCs. The edge sign may precede venous extension, especially in metastatic cases, indicating the nature of the lesion. These findings potentially may alter disease management, expediting the decision for surgery; however, prospective multicenter studies are needed to confirm their clinical impact. KEY POINTS: Question What is the prevalence of venous extension in malignant adrenal lesions-whether primary or secondary-and how can early involvement be recognized on imaging? Finding Adrenal vein involvement occurred similarly in ACCs (21.4%) and metastases (14.6%). Early extension may be preceded by the adrenal edge sign in 25% of cases. Clinical relevance Adrenal vein involvement occurs in both primary and metastatic adrenal lesions, with a tendency to be more prevalent in adrenocortical carcinomas. The 'edge sign' may precede venous extension in malignant lesions, aiding both diagnosis and therapeutic planning.