Syndromes associated with vascular tumors and malformations: a pictorial review.

Use of the International Society for the Study of Vascular Anomalies (ISSVA) classification system has been strongly recommended in recent years because of the need for separate therapeutic measures for patients with vascular tumors and malformations. In the ISSVA classification system, vascular tumors, which are neoplastic, are distinguished from vascular malformations, which are caused by vascular structural anomalies and are not neoplastic, on the basis of the presence or absence of neoplastic proliferation of vascular endothelial cells. It is important that radiologists be familiar with the development, diagnosis, and treatment of vascular tumors and malformations, especially the imaging features of low- and high-flow vascular malformations. Some vascular tumors and malformations develop in isolation, whereas others develop within the phenotype of a syndrome. Syndromes that are associated with vascular tumors include PHACE syndrome. Syndromes that are associated with vascular malformations include Sturge-Weber, Klippel-Trénaunay, Proteus, blue rubber bleb nevus, Maffucci, and Gorham-Stout syndromes, all of which demonstrate low flow, and Rendu-Osler-Weber, Cobb, Wyburn-Mason, and Parkes Weber syndromes, all of which demonstrate high flow. Because imaging findings may help identify such syndromes as systemic, it is important that radiologists familiarize themselves with these conditions.