Chapter 462

Vascular tumors comprise a small percentage of tumors in children and adults. Classifying these tumors can be difficult because of the rarity of these lesions and their diverse morphologic appearance and clinical behavior. In the pediatric population, these tumors are not independently stratified, leading to further problems with diagnosis. The most common vascular tumors (hemangiomas) are benign and have a diverse spectrum of clinical phenotypes. Similarly, the rarer vascular tumors can be benign or malignant with some overlap adding to diagnostic and treatment dilemmas (Table 462-1).

Table 462-1. Classification of Vascular Neoplasms

Infantile hemangiomas are discussed in more detail in Chapter 364. Hemangiomas are composed of a proliferating, clonal population of endothelial-like cells.1 These tumors can involve any organ; can occur as single, diffuse, or disseminated lesions; and can be associated with complicated syndromes.1,2 Tumor endothelial cells express GLUT1 as determined by immunohistochemistry.4 Most hemangiomas are uncomplicated and do not require therapeutic intervention. However, a significant percentage of hemangiomas produce clinical symptoms because of lesion size, location, or hemodynamic effects.5

Treatment of infantile hemangiomas is designed to control growth, minimize deformity, and preserve function. Systemic pharmacotherapy is used to treat large lesions, those that present a surgical challenge, or lesions causing functional or life-threatening problems. Steroids used at high doses (2–5 mg/kg/day) for long periods of time (3–12 months) have been the mainstay of therapy for symptomatic hemangiomas.6-10 Other agents with reported activity in treating hemangiomas include vincristine and α-interferon.11-19

Infants with multiple (> 5) cutaneous hemangiomas can have focal visceral tumors involving the liver, spleen, lung, brain, and intestines. The liver is the organ most commonly affected and its involvement can lead to serious complications such as hepatomegaly with liver dysfunction, compartment syndrome (intraparenchymal hypertension), congestive heart failure, and anemia/mild thrombocytopenia.20-22 Therefore, infants presenting with multiple cutaneous hemangiomas should undergo further evaluation, including ultrasound evaluation of the abdomen. If liver lesions are found, magnetic resonance imaging (MRI) is indicated to better characterize and quantify the lesions. Liver hemangiomas can also occur without cutaneous lesions, which make them more difficult to diagnose. Symptomatic liver hemangiomas have been treated successfully with steroids, vincristine, and interferon therapy.

A recent report demonstrated an association between infantile hemangiomas and severe hypothyroidism.23 High levels of type 3-iodothyronine deiodinase activity were found in the hemangioma tissue, causing an accelerated uptake of thyroid hormone. Infants with large hemangiomas, particularly hepatic hemangiomas, should therefore be screened for hypothyroidism. Since such patients may require extraordinarily high doses of thyroid replacement, they should be followed by a pediatric endocrinologist. Unidentified, severe hypothyroidism can lead ...

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