 Introduction/Background Soft tissue vascular anomalies (VAs) may be diagnosed prenatally or at any time during life [1-3]. Anomalies of the soft tissues may be located in the extremities, face, scalp, neck, airway, thoracoabdominal wall, mediastinum, lungs, and abdomen (mesentery, retroperitoneum, and viscera). They may be associated with syndromes and may signal the presence of internal vascular lesions. Soft tissue VAs are subdivided into broad categories of vascular malformations (VMs) and vascular tumors (VTs). VTs are true neoplasms with increased mitotic activity and endothelial cell turnover; VMs are composed of abnormal or defective formation of vascular tissue [4] (see Appendix 1). The prevalence of VMs varies by type: venous malformations (70%), lymphatic malformations (12%), arteriovenous malformations (AVMs) (8%), combined malformation syndromes (6%), and capillary malformations (4%) [5]. They may be divided into simple (further divided into low-flow or fast-flow VMs) or combined. Low- flow, simple VMs often contain 1 type of low-flow vessel: capillary, lymphatic, or venous vessel. AVMs or arteriovenous fistulas (AVFs) are fast-flow, simple VMs. Combined VMs are composed of more than 2 types of simple VM components and may be named for a major vessel [4,6]. Complex anomalies may be associated with overgrowth syndromes, which are often composed of infiltrative venous and lymphatic tissues through thickened subcutaneous fat affecting the trunk and/or limbs [7-10] (see Appendix 2). VTs are divided into masses that behave in a benign, locally aggressive, borderline, or malignant manner. The most common benign VT is infantile hemangioma, which presents in the newborn period, whereas other VTs, malignant and other aggressive vascular lesions, may be diagnosed at any age. Most benign lesions are observed or treated in a noninvasive manner.
Soft Tissue Vascular Anomalies Vascular Malformations and Infantile Vascular Tumors Non CNS Child.  Introduction/Background Soft tissue vascular anomalies (VAs) may be diagnosed prenatally or at any time during life [1-3]. Anomalies of the soft tissues may be located in the extremities, face, scalp, neck, airway, thoracoabdominal wall, mediastinum, lungs, and abdomen (mesentery, retroperitoneum, and viscera). They may be associated with syndromes and may signal the presence of internal vascular lesions. Soft tissue VAs are subdivided into broad categories of vascular malformations (VMs) and vascular tumors (VTs). VTs are true neoplasms with increased mitotic activity and endothelial cell turnover; VMs are composed of abnormal or defective formation of vascular tissue [4] (see Appendix 1). The prevalence of VMs varies by type: venous malformations (70%), lymphatic malformations (12%), arteriovenous malformations (AVMs) (8%), combined malformation syndromes (6%), and capillary malformations (4%) [5]. They may be divided into simple (further divided into low-flow or fast-flow VMs) or combined. Low- flow, simple VMs often contain 1 type of low-flow vessel: capillary, lymphatic, or venous vessel. AVMs or arteriovenous fistulas (AVFs) are fast-flow, simple VMs. Combined VMs are composed of more than 2 types of simple VM components and may be named for a major vessel [4,6]. Complex anomalies may be associated with overgrowth syndromes, which are often composed of infiltrative venous and lymphatic tissues through thickened subcutaneous fat affecting the trunk and/or limbs [7-10] (see Appendix 2). VTs are divided into masses that behave in a benign, locally aggressive, borderline, or malignant manner. The most common benign VT is infantile hemangioma, which presents in the newborn period, whereas other VTs, malignant and other aggressive vascular lesions, may be diagnosed at any age. Most benign lesions are observed or treated in a noninvasive manner.