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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).
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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
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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
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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.
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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 to ...