Pediatric Vascular Tumors and Malformations.

Pediatric vascular tumors and malformations, comprising a broad category of lesions often referred to as vascular anomalies, are a heterogenous group of clinicopathologically distinct entities. Pathologists, clinicians, and radiologists have traditionally lumped these lesions under the generic term, hemangioma, sometimes qualified by modifiers, such as capillary or cavernous. Advances in understanding underlying pathogenetic mechanisms support more specific classification and more specifically targeted therapies. Multidisciplinary consensus has moved toward a biologically based classification system and therapeutic approach for dealing with these lesions. This content focuses on the histologic, immunophenotypical, and clinical features that distinguish the major types of vascular tumors and malformations presenting in infancy and childhood. Pathogenic mechanisms are also briefly reviewed.