Recommended correct terminology
Correlative terminology to be avoided
Congenital vascular tumors
Port wine hemangioma
Combined malformation (without an arterial component)
Combined malformation (with an arterial component )
Vascular tumors are characterized by: (a) proliferation of endothelial cells; (b) become evident at birth in approximately 40 % of the cases (generally as precursor lesions); (c) grow rapidly after birth; and (d) show spontaneous involution after the first year of life, in a process that may span the first decade of life. The frequency ratio between women and men is 5:1 [5, 6].
In vascular malformations, the endothelial cells follow a normal cycle. These lesions are characterized by manifesting at birth in 90 % of the cases, not regressing spontaneously and growing proportionally to the child’s growth, triggered by physiological, endocrine, traumatic, or infectious stimuli. The female-to-male ratio is 1:1 [5, 6].
According to the nature of the vascular channels, vascular malformations are categorized into capillary, arterial, venous, lymphatic, or combined. They may be additionally classified as high-flow or low-flow malformations [1, 2]. High-flow malformations include arterial and arteriovenous malformations and arteriovenous fistulas, whereas low-flow malformations include venous, lymphatic, lympho-venous, and capillary malformations (Table 15.1) [3–5].
Natural History of the Disease
The lesions may be localized or diffuse and may have a self-limited course. They may cause cosmetic or functional problems such as pain, osteomuscular limitations, extrinsic airway compression, coagulopathy, hemorrhage, and deformity, in addition to compromising the function of involved organs and, in the most severe cases, leading to death .
Most of the time, vascular tumors resolve spontaneously [1, 2]. Therefore, follow-up is, in principle, the only recommendation for asymptomatic and potentially risk-free vascular tumors (including bulky hepatic hemangiomas ) .
The prognosis of vascular malformations depends on the occurrence of symptoms requiring resection, location, and extension of the lesion, surgery-induced sequelae, compression of vital structures such as the airway, heart, and central nervous system, and risk of bleeding . For example, lesions located in the central nervous system versus those in the extremities, or lesions in the ear lobe versus those affecting an entire lower limb. However, due to the minimally invasive characteristics of the therapies (embolization for high-flow malformations and direct puncture sclerotherapy for low-flow malformations), it is possible to minimize complications, when compared to the surgical treatment .
Vascular malformations often increase progressively in size. Treatment is then recommended, except in small asymptomatic lesions located in areas of difficult access .
Clinical Presentation and Diagnosis
The diagnosis in most cases is based on clinical parameters, time of manifestation, lesion characteristics, and progression . The extension of superficial lesions may be determined without much difficulty. But in those with deep extension lesions that aren’t obvious on physical exam, imaging is required for complete diagnosis .
High-flow malformations have anomalous communications between the arterial and venous systems. This communication may occur directly (arteriovenous fistula ) or through entangled vascular loops ( nidus ) without peripheral vascular resistance, directing the arterial flow to the venous sector . Arterial malformations may cause severe clinical problems such as ischemia with tissue necrosis, pain, and skin ulceration in the most severe cases secondary to sequestration of distal arterial flow, in addition to hemorrhage and heart failure caused by volume overload as a consequence of the high-output arteriovenous fistula. On physical examination, the mass is compressible and refills fast. Thrill and murmur are often detected .
In low-flow venous malformations, the mass is compressible but refills slowly. The temperature is generally unchanged, no bruit or thrill is detected, and venous stasis with varicose veins may occur. The skin covering the tumor is usually thin and bluish .
Anatomical structures may be locally or extensively affected leading to deformities. These malformations may eventually involve deeper structures such as the subcutaneous tissue or muscles in one of the limbs. In this case, the skin has a normal appearance and the malformation presents as a tumor painful to palpation .