A simple division of the<unk> s is made into low-flow and high-flow types. Low-flow<unk> s involve a single type of blood or lymph vessel, and are known as simple<unk> s; high-flow<unk> s involve an artery. There are also<unk> s that are of mixed-flow involving more than one type of vessel, such as an arteriovenous<unk> . Low-flow<unk> s include capillary<unk> s, venous<unk> s, and lymphatic<unk> s. Capillary<unk>  Port-wine stain on leg. Capillary<unk> s involve the capillaries, and are the most common type. They used to refer only to port-wine stains but now include others. Capillary<unk> s are limited to the superficial layers of the skin but they can thicken, become nodular, and sometimes become disfiguring. It has been proposed that the category of capillary<unk> s, also called vascular stains, be classified into seven major clinical types including nevus flammeus nuchae also known as nevus simplex, commonly known as stork bite or salmon patch. A capillary<unk>  is also a feature of the disorder macrocephaly-capillary<unk> . Venous<unk>  Venous<unk> s are typically ill-defined masses, coloured from pale to dark blue. They can affect any tissue in the body. The mass is soft, and easily compressed, and their blue colouring is due to the dilated anomalous involved veins. They are most commonly found in the head and neck. Venous<unk> s can often extend deeper from their surface appearance, reaching underlying muscle or bone. In the neck they may extend into the lining of the mouth cavity or into the salivary glands. A severe venous<unk>  can involve the lymph vessels as a lymphaticovenous<unk> . Lymphatic<unk>  Drawing of a microcystic lymphangioma on the left side of a boy's tongue. Lymphatic<unk> s are congenital, developing from badly-formed lymphatic vessels in early embryonic development. Abnormal development of the lymph vessels results in their failure to connect and drain into the venous system. These lymph vessels can become blocked due to the collection of lymph which forms a cyst as a mass, and are known as lymphangiomas. They can be macrocystic, microcystic, or a combination of the two. Macrocystic have cysts greater than , and microcystic lymphangiomas have cysts that are smaller than . A macrocystic lymphangioma is also known as a cystic hygroma. Cystic hygromas most often occur in the neck where they are known as nuchal hygromas. A severe venous<unk>  is known as a lymphaticovenous<unk>  that also involves the lymph vessels. Arteriovenous<unk>  3D image of an arteriovenous<unk>  shown in purple on the ring finger of a hand. Arteriovenous<unk> s occur between an artery and a vein. In the brain a cerebral arteriovenous<unk>  causes arterial blood to be directly shunted into the veins as there is an absence of a capillary bed. This carries a high risk of an intracranial hemorrhage.
Vascular malformation
Infantile hemangioma  Infantile hemangioma  1
Vascular anomaly
Developmental venous anomaly
Vascular tumor
Vascular occlusion
Congenital vertebral anomaly
Vascular ring