Vascular Malformations ...
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|Wed, 10-06-2010 - 7:19am|
Vascular Malformations..... by "animalz"...
Vascular malformations are made up of an abnormal cluster of blood vessels that occur during fetal development. Since vascular malformations are a developmental abnormality, they are always present at birth, but may not be visible until days, weeks or years after birth. The abnormality occurs as commonly in males as it does in females (as compared with hemangiomas which are much more common in females). Vascular malformations are quite different from hemangiomas in that they do not proliferate (grow). The cells within the vascular malformation do not increase in number as they do in a hemangioma. Instead, the size of the existing cells and blood vessels in the vascular malformation expand. This is known as hypertrophy. Vascular malformations therefore do not grow rapidly during the first year of life. Some vascular malformations do however grow much more rapidly than others. Vascular malformations are further subdivided according to the type of vessel they are made up of. Growth of these lesions is by hypertrophy (enlargement of vessels) rather than hyperplasia (increase in the number of cells). In some (high-grade lesions) the rate of growth is more rapid. Other factors may stimulate periods of rapid growth such as infection, trauma and hormonal changes. Enlargement of the lesion is common at puberty and other periods of hormonal modulation. Infection and trauma may also result in sudden enlargement of a lymphatic malformation. Midline Venular (Capillary) malformations are flat macular stains such as 'stork bites', 'salmon patches', and 'angel kisses'. The very small veins (venules) of this lesion are always situated in the midline. These usually fade within the first year of life. . Venular malformations are known as portwine stains, and previously referred to as capillary malformations. The venules of this lesion are located in the superficial layer of the dermis. Venous malformations are often erroneously referred to as cavernous hemangiomas. They are comprised of large dilated veins in the subcutaneous tissue. Lymphatic malformations were previously known as lymphangioma, hemangiolymphangioma, and cystic hygroma. These lesions form from dilated lymph vessels. Mixed malformations- two or more types of vessels are affected with this lesion: arteriovenous, arteriovenous-capillary, venous-lymphatic, venous-lymphatic capillary, and venular venous malformations.
Proliferation and Involution never occurs in vascular malformations. Instead, slow steady growth is normal.
Incidence of vascular malformations shows no gender preference.
Venular malformations occur in 0.3 percent of births.
Lymphatic malformations - Ninety percent are visible within two years after birth.
Sites- Midline venular (capillary) malformations usually occur in the head and neck area... Venular malformations occur on the head and neck as the most common sites. Lips, tongue, buccal mucosa, buccal fat space and from upper lip to nasal vestibule are common... Venous malformations commonly occur on the head or extremities... Lymphatic malformations commonly occur in the head and neck area... Mixed malformations can occur anywhere on the body...