Complex vascular anomalies.

The classification system for vascular anomalies now used by experts worldwide comprises two distinct disease entities that differ in their biologic and pathologic features: vascular tumors and vascular malformations. Vascular tumors include infantile and congenital hemangiomas, tufted angiomas, and kaposiform hemangioendotheliomas. Infantile hemangiomas, the most common vascular anomaly, generally have a predetermined life cycle (proliferation and subsequent involution). GLUT-1, a glucose transporter, is a marker for these specific lesions during all phases of development. Vascular malformations are classified according to their vascular tissue of origin and include capillary, venous, arteriovenous, lymphatic, and mixed malformations. Complex lymphatic malformations and complex mixed malformations, which may have most vascular components, are the most difficult vascular malformations to successfully treat. These lesions are present at birth and often expand or grow in response to trauma, infection, or hormonal changes. Imaging advancements have enabled more accurate assessments and improved management of vascular anomalies. In addition, many lesions are now being managed with targeted pharmacologic therapy. Propranolol and steroids are used for complex or disfiguring tumors, and new anti-angiogenesis inhibitors such as sirolimus are selectively used to treat lymphatic and venous lymphatic malformations that are poorly responsive to sclerotherapy, embolization, and surgical excision. Multimodal therapies are often essential for complex lesions and require the combined expertise of an interdisciplinary team.