With a prevalence of 4–6%, infantile haemangiomas (IH) represent the most common vascular tumours in infancy. While most IH tend to resolve spontaneously, some can cause life-threatening complications, undergo painful ulceration or lead to permanent disfigurement. The past years have witnessed considerable advances in our understanding of pathogenesis, clinical presentation and therapy of IH: both abnormal angiogenesis and vasculogenesis contribute to the neovascularization in IH. Hypoxia has been identified as an important stimulus for angiogenesis. Abnormal signalling via vascular endothelial growth factor (VEGF) receptors on haemangioma stem cells[2, 3] directs their proliferation and differentiation.
Many different clinical forms of IH have been separated. The glucose transporter 1 (GLUT1) has been identified as the key antigen for the differentiation between IH (where it is expressed throughout all developmental stages) and other vascular tumours or malformations, and also helps to differentiate IH from congenital haemangiomas. Segmental haemangiomas represent a distinct subgroup of IH frequently associated with vascular, cardiac and other anomalies that require careful screening investigations.
The most amazing advance in recent years, however, was the serendipitous discovery of the beneficial effects of propranolol in the proliferative phase of IH, which has revolutionized their therapy. With a response rate of 98% even in the most complicated types of IH, and a very good safety record, it has become the mainstay of therapy, replacing (or marginalizing) former ‘standard’ treatment options such as corticosteroids or laser procedures (much to the regret of many laserologists).
In this first collection of scholarly reviews Dr Shoshana Greenberger and Professor Joyce Bischoff bring us up to date with what is known about the major cell types in IH and the molecular pathways that appear to play a role in haemangiogenesis. Dr Minnelly Luu and Professor Ilona Frieden review the natural history, specific growth characteristics and potential complications associated with IH, in order to aid decisions on whom and when to treat.