What is a Hemangioma? What are the Causes of Hemangioma?

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Hemangioma is a benign tumor formed by the abnormal growth and buildup of blood vessels. The cause of hemangioma is unknown.

Hemangioma usually appears on the skin, especially on the head, face and neck. It may form in the top skin layers (capillary) or deeper in the skin (cavernous). It may also appear on the internal organs like liver, spine and vertebrae. The term hemangioma comes from Greek words meaning "blood-vessel-tumor".

These lesions are the most common benign tumors in children. These lesions may be present at birth as birth marks having faint reddened areas or develop after birth in the early months. Usually these tumors grow rapidly for about twelve months. Then there is a resting phase with little change in appearance for another twelve months. Then the involution phase starts and causes the lesions to diminish in size and disappear in ten years. In rare cases it may persist beyond ten years.

Hemangiomas and vascular malformations

     Earlier the term hemangioma was used to denote a variety of vascular lesions of infancy and childhood. Mulliken JB. and Glowacki J. categorized these conditions into  hemangiomas and vascular malformations. Hemangiomas have a proliferating phase characterized by endothelial hyperplasia which causes rapid growth of tumor. Then there is an involution phase with histological fibrosis and fat deposition followed by a regression phase. Under the microscope, these lesions appear as aggregates of closely packed capillaries filled with blood having endothelial lining.

     Vascular malformations are usually seen at birth and they grow proportionately with the child-growth. Vascular malformations consist of abnormal arteries, veins and capillaries and are essentially permanent. This categorization helps in deciding on the type of treatment required, if any.

Causes of hemangioma

     The exact cause of this benign tumor is unknown. Several views and hypotheses have been suggested as possible causes of these lesions. Several studies suggested a role for the estrogen hormone for their development. A study suggested that higher levels of estrogen circulating in the infant blood coupled with the localized tissue hypoxia may be a cause or a triggering factor for these lesions.

     Another study hypothesized that embolisms of maternal placenta on to dermis of fetus may be the cause of hemangioma. However this view was contradicted by the DNA studies of the mother and lesion tissue. More research is required to know the cause of the explosive rate of growth of these tumors.

     Hemangioma is more prevalent in Caucasian infants than in Asian infants. It is rarely found in African-American infants. About 5% of Caucasian infants are born with these lesions. The cause of this ethnic variation is unknown. The low amount of melanocytes present in fairer skin may be a cause for the development of these tumors. Premature infants and small infants are more prone to have or develop these tumors. Further, when compared to males more number of female infants are affected.

     These tumors have potential for complications and permanent scarring. The risks involved include visual obstruction, breathing obstruction, ear canal obstruction facial disfigurement or bleeding ulceration. The tumors of the internal organs can lead to pain, impaired organ function or failure. When the tumor is very large it may create excess load and stress on the heart. The presence of lesions may have a psychological impact on the child and cause emotional distress and behavioral problems. Hence the presence of hemangioma in infants requires medical advice and early treatment.

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What is a Hemangioma? Causes of Hemangioma.

References:
 1. Haggstrom AN et al. (September 2006). Pediatrics 118 (3): 882–7. doi:10.1542/peds.2006-0413. PMID 16950977. "Prospective study of infantile hemangiomas: clinical characteristics predicting complications and treatment".