In the classification of vascular anomalies, the group of vascular tumors, consisting of true tumors with corresponding active proliferation of cells (especially endothelial cells), contrasts with the group of vascular malformations, which are dysplastic anomalies in the formation and maturation of vessels and show no or only minimal cell proliferation.
In addition to the significantly higher cell density that characterizes vascular tumors as solid, space occupying lesions, and the active proliferation of endothelial cells, vascular tumors also exhibit different growth dynamics than the more static vascular malformations that grow proportionally with the patient. Vascular tumors usually develop after birth, often later in life, from previously unremarkable tissue. They usually grow progressively larger. However, in contrast to most vascular tumors, infantile hemangiomas regress spontaneously.
Vascular tumors are generally divided into benign, intermediate (semi-malignant) and malignant tumors and are very rare except for the very common infantile hemangioma.