Vascular lesions of bone in children, adolescents, and young adults. A clinicopathologic reappraisal and application of the ISSVA classification.

Vascular lesions of bone are rare and their terminology is not standardized. Herein, we report 77 patients with such lesions in order to characterize their morphologic spectrum and the applicability of the International Society for the Study of Vascular Anomalies (ISSVA) classification. In this system, malformations are structural anomalies distinguishable from tumors, which are proliferative. The radiologic images/reports and pathologic materials from all patients were reviewed. All lesions were either restricted to bone or had minimal contiguous soft tissue involvement with the exception of some multifocal lymphatic lesions that extensively affected soft tissue and/or viscera. We found that certain lesions of bone often regarded as tumors should be classified as malformations. Malformations (n = 46) were more common than tumors (n = 31); lymphatic and venous malformations were equally frequent. In the tumor category, hemangioendothelioma and epithelioid hemangioma were the most common. We also describe new vascular entities that arise in or involve bone. Utilizing the ISSVA approach, the diverse and often contradictory terminology of vascular lesions of bone can be largely eliminated. Standardized nomenclature is critical for scientific communication and patient management, and we hereby recommend the ISSVA classification be applied to vascular lesions of bone, just as for skin, soft tissue, and viscera.