|Classification and external resources|
A small hemangioma of infancy
|ICD-10||D18.0 (ILDS D18.010)|
A hemangioma is a benign, and usually a self-involuting tumor, (swelling or growth) of the endothelial cells that line blood vessels and is characterised by increased number of normal or abnormal vessels filled with blood. It usually appears during the first weeks of life and generally resolves by age 10. In more severe cases hemangiomas may leave residual tissue damage. In infancy, it is the most common tumor. The word "hemangioma" comes from the Greek haema- (αίμα), "blood"; angeio (αγγείο), "vessel"; -oma (-ωμα), "tumor".
The terminology used to define, describe and categorize vascular anomalies, abnormal lumps made up of blood vessels, has changed. The term hemangioma was originally used to describe any vascular tumor-like structure, whether it was present at or around birth or appeared later in life. Mulliken et al. categorized these conditions into two families: a family of self-involuting tumors, growing lesions that eventually disappear, and another family of malformations, enlarged or abnormal vessels present at birth and essentially permanent. The importance of this distinction is that it makes it possible for early-in-life differentiation between lesions that will resolve versus those that are permanent. Examples of permanent malformations include port-wine stains (capillary vascular malformation) and masses of abnormal swollen veins (venous malformations). Unfortunately[to whom?] it is taking some time for other branches of medicine to adopt the new terminology which causes confusion. The Mulliken categorisation has received major confirmation following discovery of the Glut-1 marker (see below).
Signs and symptoms 
Hemangiomas are connected to the circulatory system. The appearance depends on location. If they are on the surface of the skin, they are reminiscent of a ripe strawberry (hence, they are sometimes referred to as "strawberry hemangiomas"); however, if they are just under the skin they present as a bluish swelling. Sometimes they grow in internal organs such as the liver, larynx, or small and large intestine. In most cases, hemangiomas will disappear over time. Some are formed during gestation; the most common are not congenital, but appear during the first few weeks of life. They are often initially misdiagnosed as a scratch or bruise; but the correct diagnosis becomes obvious with further growth. Typically, at the earliest phase in a superficial lesion, one will see a bluish red area with obvious blood vessels and surrounding pallor. Sometimes they present as a flat red or pink area. Hemangiomas are the most common childhood tumor, occurring in approximately ten percent of Caucasians, and are less prevalent in other ethnicities. Females are three to five times as likely to have hemangiomas as males. Hemangiomas are also more common in twin pregnancies. Approximately 80% are located on the face and neck, or on the legs and arms; with the next most prevalent location being the liver. In infants, It may present itself soon after birth and is different than other vascular abnormalities present. They grow to around 80% of their maximum size in the first 3 months and most reach maximum size at around 5 months.
Hemangioma on the scalp of a two year old female, in the "rest stage"
The cause of hemangioma is currently unknown; however, several studies have suggested the importance of estrogen signaling in hemangioma proliferation. In 2007, a paper from the Stanford Children's Surgical Laboratory revealed that localized soft tissue hypoxia coupled with increased circulating estrogen after birth may be the stimulus. There is also a hypothesis presented by researchers at Harvard and the University of Arkansas that maternal placenta embolizes to the fetal dermis during gestation resulting in hemangiomagenesis. However, researchers at Duke University conducted genetic analyses of single-nucleotide polymorphism in hemangioma tissue compared to the mother's DNA that contradicted this hypothesis. More research is required in order to fully understand the explosive nature of hemangioma growth, which will hopefully yield targeted therapeutics to treat its most complicated presentations.
Review of Histology 
Under the microscope, hemangiomas are unencapsulated aggregates of closely packed, thin-walled capillaries, usually with endothelial lining. Blood-filled vessels are separated by scant connective tissue. Their lumens may be thrombosed and organized. Hemosiderin pigment due to vessel rupture sometimes can be noticed. Glut1 is a histochemical marker, highly specific for Haemangioma and can be used to differentiate Haemangioma from vascular malformations.
The vast majority of hemangiomas are not associated with complications. Hemangiomas may break down on the surface, called ulceration. If the ulceration is deep, significant bleeding may occur in rare occasions. Ulceration on the deeper area can be painful and problematic. If a hemangioma develops in the larynx, breathing can be compromised. A hemangioma can grow and block one of the eyes, causing an occlusion amblyopia. Very rarely, extremely large hemangiomas can cause high-output heart failure due to the amount of blood that must be pumped to excess blood vessels. Lesions adjacent to bone can also cause erosion of the bone.
The most frequent complaints about hemangiomas, however, stem from psychosocial complications: the condition can affect a person's appearance and can provoke attention and malicious reactions from others. Particular problems occur if the lip or nose is involved, as distortion can be difficult to treat surgically. The potential for psychological injury develops from school age onward. It is therefore important to consider treatment prior to school if adequate spontaneous improvement has not occurred.
Most hemangiomas disappear without treatment, leaving minimal or no visible marks. Large hemangiomas can leave visible skin changes secondary to severe stretching of the skin or damage to surface texture. When hemangiomas interfere with vision, breathing, or threaten significant cosmetic injury (facial lesions and in particular, nose and lips), they are usually treated.
Until recently, the mainstay of treatment was oral corticosteroid therapy, but there are now alternative treatments. A randomized trial showed that the beta-blocker propranolol reduced severe hemangiomas in infants. The topically applied beta blocker solution/gel Timolol is also being trialled for small facial hemangiomas that do not justify systemic treatment. Other treatments that have been used include interferon or vincristine. They may be considered if first-line therapy fails.
Surgical removal is sometimes indicated, particularly if there has been delay in commencing treatment and structural changes have become irreversible. Surgery may also be necessary to correct distortion of facial features, again in the case of inadequate or failed early medical intervention. Blockage of the airway will often require a tracheostomy to be performed, which involves the insertion of an external airway through the front of the neck into the trachea below the level of the obstruction.
Smaller raised lesions are sometimes treated with injection of corticosteroid directly into the lesion. A pulsed dye laser can be useful for very early, flat, superficial lesions, if they appear in cosmetically significant areas or for those lesions that leave residual surface blood vessels in the case of incomplete resolution. Sometimes a pulsed dye laser can be used to accelerate healing. Unfortunately, raised lesions or lesions under the skin do not respond to laser treatment. Ulceration will usually heal with topical medication and special dressings under medical supervision. Applying pressure is not beneficial, thus not recommended.
Hemangiomas go through three stages of development and decay:
- In the proliferation stage, a hemangioma grows very quickly. This stage can last up to twelve months.
- In the rest stage, there is very little change in a hemangioma's appearance. This usually lasts until the infant is one to two years old.
- In the involution phase, a hemangioma finally begins to diminish in size. 50% of lesions will have disappeared by 5 years of age, and the vast majority will have gone by 10
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