A vascular anomaly is any of a range of lesions from a simple birthmark to a large tumor that may be disfiguring. They are caused by a disorder of the vascular system.[1] A vascular anomaly is a localized defect in blood vessels or lymph vessels. These defects are characterized by an increased number of vessels, and vessels that are both enlarged and heavily curved. Some vascular anomalies are congenital, others appear within weeks to years after birth, and others are acquired by trauma or during pregnancy. Inherited vascular anomalies are also described and often present with a number of lesions that increase with age. Vascular anomalies can also be a part of a syndrome.[citation needed]
The estimated prevalence of vascular anomalies is 4.5%.[2] Vascular anomalies can occur throughout the whole body, but in 60% of patients they are localized in the head and neck region.[3] Vascular anomalies can present in various ways: when situated deep below the skin, they appear blue, and are often called cavernous. Superficial vascular anomalies appear as red-coloured stains and are associated with vascular anomalies affecting the dermis. Historically, vascular anomalies have been labeled with descriptive terms, according to the food they resembled (port wine, strawberry, cherry, salmon patch). This imprecise terminology has caused diagnostic confusion, blocked communication and even caused incorrect treatment, as it does not differentiate between various vascular anomalies.[4] However, in 1982, Mulliken introduced a classification that replaced these descriptive terms and gave direction to the management of various vascular anomalies. This classification, based on clinical features, natural history and cellular characteristics, divides vascular anomalies into two groups: vascular tumors and vascular malformations.[5] Although vascular tumors and vascular malformations can resemble each other, there are important differences between both.