The ISSVA Classification for Vascular Anomalies: The History and Position Status of Venous Malformations

Abstract

So-called “hemangiomas” mainly seen in children and adolescents contain various diseases biologically distinct from each other. To classy such vascular lesions according to the pathogenetical etiology, the ISSVA classification first adopted in 1996 divided them into proliferative vascular tumors and vascular malformations. Vascular malformations are developmental errors in vascular morphogenesis, and consist of various vascular components including capillary (CM), lymphatic (LM), venous (VM), arteriovenous malformations (AVM), and combined variants. They can occur in any part of the body, and generally progress or enlarge proportionally to age. Because additional disease entities or causal genes have been identified in the last decade, the ISSVA classification was revised in 2014 from the perspective of molecular biology. In the new ISSVA classification, the vascular tumors are classified as benign, locally aggressive or borderline, and malignant. The vascular malformations are divided into four sections: simple-type malformations, combined-type malformations, malformations of major named vessels, and malformations associated with other abnormalities. Among them, VMs are included in the simple-type malformations, composed of common sporadic VMs and rare inheritable VMs including familial VM cutaneo-mucosal (VMCM), blue rubber bleb nevus syndrome (Bean syndrome), glumuvenous malformation (GVM), and cerebral cavernous malformations (CCM). In clinical practice of venous diseases, it is important to recognize the ISSVA classification for proper diagnosis and appropriate management of vascular malformations.