Associated Structural Abnormalities
Etiology and Pathogenesis
The cause of hemangioma is currently unknown;
A hemangioma consists of an abnormally dense group of extra blood vessels. It's not clear what causes the blood vessels to group together, although there may be a hereditary component involved.
Although hemangiomas usually affect the skin, isolated visceral lesions also occur.
The occurrence of multiple IHs is called hemangiomatosis. In this setting, the cutaneous lesions are usually tiny (<5 mm) and domelike, but some may have the more typical appearance of a single tumor. Occult visceral lesions may be present when multiple cutaneous IHs (usually five or more) are found. Screening ultrasonography may be indicated. The liver is the most frequently involved location.
90% of hemangiomas may be diagnosed by history and physical exam.
Radiographic studies can aid in the diagnosis in the 10% of patients whose diagnosis is still in question after the history and physical exam.
¤ Ultrasonography is an easy and cost-effective way of differentiating hemangioma from slow-flow vascular anomalies.
¤ Radionucide scanning with technetium Tc 99m-tagged red blood cells may be used to locate multiple hemangiomas in the central nervous system or gastrointestinal tract.
¤ MRI is the radiologic modality of choice for differentiating vascular anomalies.
Congenital abnormalities are rarely associated with IH, but larger hemangiomas and those encountered in the midline merit attention.
A subgroup of patients with IH exhibits associated structural anomalies of the brain (e.g., posterior fossa abnormalities), cerebral vasculature (e.g., hypoplasia or absent carotid and vertebral vessels, aneurysms), eye (e.g., cataracts and optic nerve hypoplasia), aorta (e.g., coarctation), and chest wall defects (e.g., sternal clefts) in the neurocutaneous disorder called PHACES syndrome (Posterior fossa malformations, Hemangioma, Arterial anomalies, Cardiac defects, Eye anomalies, and Sternal defects).
Anorectal and genitourinary anomalies can occur with IH of the pelvis or perineum, sometimes as part of PELVIS syndrome (Pelvic hemangioma, External genital malformations, Lipomeningocele, Vesicorenal, Imperforate anus, Skin tags).
The majority of IHs require no specific treatment other than observation. Even if the proper decision is not to intervene, this does not mean that nothing should be done. The consultant plays a crucial role in providing guidance and support. Regularly scheduled follow-up is imperative. Parents should be reassured by showing them photographs of the tumor in its proliferative, involuting, and involuted phases. Patients are followed closely through the proliferative phase of growth.