State of the art: imaging of solid renal lesions

Renal lesions are frequently and increasingly detected as incidentalomas on different imaging techniques of the abdomen in various clinical contexts and concerning all age groups of patients. In this context, the radiologist’s expertise plays a key role in accurately characterizing renal lesions leading to the optimal patient management, in order to efficiently treat malignant lesions while avoiding unnecessary interventions for benign lesions or in patients with underlying comorbidities limiting radical treatment. Cystic lesions are characterized by the Bosniak classification system and are out of the scope of this review. Solid renal lesions exhibit various morphological and functional imaging features that facilitate their characterization and contribute to the differentiation between benign and malignant entities. The aim of this review is to provide radiologists with a guide for accurate and up-to-date interpretation of solid renal lesions, leading to the most probable diagnosis and optimal management. This review begins with an overview of imaging modalities for renal lesions, followed by an analysis of key imaging features relevant to renal lesion characterization. Additionally, we present a literature-based analysis of the principal findings of relevant solid renal lesions. Finally, we propose a diagnostic algorithm to guide the radiologist’s interpretation.