A vascular malformation is a type of

vascular anomaly A vascular anomaly is any of a range of lesions from a simple birthmark to a large vascular tumor, tumor that may be disfiguring. They are caused by a disorder of the vascular system. A vascular anomaly is a localized defect in blood vessels or ly ...

. They may cause aesthetic problems as they have a growth cycle, and can continue to grow throughout life. Vascular malformations of the brain include those involving

capillaries A capillary is a small blood vessel, from 5 to 10 micrometres in diameter, and is part of the microcirculation system. Capillaries are microvessels and the smallest blood vessels in the body. They are composed of only the tunica intima (the in ...

, and those involving the

vein Veins () are blood vessels in the circulatory system of humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are those of the pulmonary and feta ...

s and

arteries An artery () is a blood vessel in humans and most other animals that takes oxygenated blood away from the heart in the systemic circulation to one or more parts of the body. Exceptions that carry deoxygenated blood are the pulmonary arteries in ...

. Capillary malformations in the brain are known as

cerebral cavernous malformations Cavernous hemangioma, also called cavernous angioma, venous malformation, or cavernoma, is a type of venous malformation due to endothelial dysmorphogenesis from a lesion which is present at birth. A cavernoma in the brain is called a cerebra ...

or ''capillary cavernous malformations''. Those involving the mix of vessels are known as

cerebral arteriovenous malformation A cerebral arteriovenous malformation (cerebral AVM, CAVM, cAVM, brain AVM, or BAVM) is an abnormal connection between the arteries and veins in the brain—specifically, an arteriovenous malformation in the cerebrum. Signs and symptoms The mos ...

s (AVMs or cAVMs). The arteriovenous type is the most common in the brain.

Types

The International Society for the Study of Vascular Anomalies (ISSVA) classification has 5 types of Vascular Malformation. * denotes high-flow malformation Vascular malformations can also be divided into ''low-flow'' and ''high-flow'' types. Low-flow malformations involve a single type of blood or lymph vessel, and are known as ''simple vascular malformations''; high-flow malformations involve an artery. There are also malformations that are of mixed-flow involving more than one type of vessel, such as an

arteriovenous malformation An arteriovenous malformation (AVM) is an abnormal connection between arteries and veins, bypassing the capillary system. Usually congenital, this vascular anomaly is widely known because of its occurrence in the central nervous system (usually ...

. Low-flow vascular malformations include ''capillary malformations'', ''venous malformations'', and ''lymphatic malformations''.

Simple Types

Capillary malformation

Capillary malformations involve the

, and are the most common type. They used to refer only to

port-wine stain A port-wine stain (''nevus flammeus'') is a discoloration of the human skin caused by a vascular anomaly (a capillary malformation in the skin). They are so named for their coloration, which is similar in color to port wine, a fortified red wi ...

s but now include others. Capillary malformations 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 malformations, 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 malformation is also a feature of the disorder

macrocephaly-capillary malformation Macrocephaly-capillary malformation (M-CM) is a multiple malformation syndrome causing abnormal body and head overgrowth and cutaneous, Blood vessel, vascular, neurologic, and limb abnormalities. Though not every patient has all features, commonl ...

. An example of capillary malformation is cerebral cavernous malformations. This disease is linked to the central nervous system (brain, eye, spinal cord). They are abnormal clusters of closely packed, thin-walled blood vessels that usually form caverns. The lesions contain slow-moving or clotted blood. Lesions in the brain and spinal cord are particularly fragile and likely to bleed. Lymphangioma of the left side of the tongue Wellcome L0062760

Lymphangioma of the left side of the tongue Wellcome L0062760

Lymphatic malformation

Lymphatic malformations are congenital, developing from badly-formed lymphatic vessels in early

embryonic development In developmental biology, animal embryonic development, also known as animal embryogenesis, is the developmental stage of an animal embryo. Embryonic development starts with the fertilization of an egg cell (ovum) by a sperm, sperm cell (spermat ...

. 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 lymphatic malformationss. They can be macrocystic, microcystic, or a combination of the two. Macrocystic have cysts greater than , and microcystic lymphatic malformation have cysts that are smaller than . A severe venous malformation is known as a lymphaticovenous malformation that also involves the lymph vessels.

Venous malformations

Venous malformations are the type of vascular malformation that involves the veins. They 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 gland The salivary glands in many vertebrates including mammals are exocrine glands that produce saliva through a system of ducts. Humans have three paired major salivary glands ( parotid, submandibular, and sublingual), as well as hundreds of min ...

s. They are the most common of the

vascular malformations A vascular malformation is a type of vascular anomaly. They may cause aesthetic problems as they have a growth cycle, and can continue to grow throughout life. Vascular malformations of the brain include those involving capillaries, and those inv ...

. A severe venous malformation can involve the lymph vessels as a ''lymphaticovenous malformation''. 3D Picture of Hand

Arteriovenous malformation

Arteriovenous malformation An arteriovenous malformation (AVM) is an abnormal connection between arteries and veins, bypassing the capillary system. Usually congenital, this vascular anomaly is widely known because of its occurrence in the central nervous system (usually ...

s occur between an artery and a vein. In the brain a

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 Intracranial hemorrhage (ICH) refers to any form of Hemorrhage, bleeding Internal bleeding, within the Human skull, skull. It can result from trauma, vascular abnormalities, hypertension, or other medical conditions. ICH is broadly categorized ...

Arteriovenous fistula

Combined Types

Combined types are defined as two or more vascular malformations found in one lesion. Examples of combined types include lymphatic-venous malformation (LVM) or capillary-venous-arteriovenous malformation (VAVM).

Terminology

The International Society for the Study of Vascular Anomalies (ISSVA) classification is a basic and systematic classification of vascular anomalies with international acceptance. As such terms such as "Lymphangioma" and "Cystic Hygroma", which were used widely in the past, are outdated. Newer research may only reference ISSVA terminology and, as a consequence, sources of information can be missed by doctors and patients unaware of the ISSVA convention.

References

{{Vascular anomalies Angiogenesis Vascular anomalies