Peripheral and soft-tissue vascular malformations in the 2025 ISSVA classification: a practical MRI approach

The 2025 update of the International Society for the Study of Vascular Anomalies (ISSVA) classification introduced several imaging-relevant changes, including the recognition of potentially unique vascular anomalies. Although the main framework for vascular tumors remains unchanged, with continued subdivision into benign, borderline, and malignant tumors, the most radiologically relevant structural changes concern vascular malformations, which were reorganized into fast-flow lesions, slow-flow lesions, and developmental anomalies of named vessels. These updates are important for radiologists because imaging plays a central role in assessing hemodynamic characteristics, defining lesion extent, and identifying findings relevant to procedural planning and multidisciplinary management. This educational review presents an author-derived four-step framework that organizes established MRI observations for peripheral and soft-tissue vascular malformations according to the structure and terminology of the 2025 ISSVA classification, including hemodynamic assessment, vascular components, tissue composition, lesion extent, and treatment-relevant anatomy. KEY POINTS: Question Imaging-relevant organizational and terminology changes in the 2025 ISSVA classification require practical guidance for consistent MRI assessment and reporting of peripheral and soft-tissue vascular malformations. Findings An author-derived four-step, flow-based framework organizes hemodynamics, dominant vascular components, tissue composition, lesion extent, and treatment-relevant anatomy into structured MRI assessment. Critical relevance statement The MRI-focused framework provides a practical way to apply the 2025 ISSVA classification consistently in image interpretation, terminology, and reporting of peripheral and soft-tissue vascular malformations.