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Vascular anomalies commonly present as birthmarks.1 Their classification has historically been problematic, with contradictory and confusing terminology and nomenclature. Although several classification schemes exist, the most widely accepted and comprehensive is the International Society for the Study of Vascular Anomalies (ISSVA) classification, updated in 2014, to incorporate clinical, imaging, histologic and (where known) genetic characteristics.1,2 Vascular anomalies are broadly divided into vascular malformations and vascular tumors.3 Vascular malformations (see Chap. 147) are errors of vascular morphogenesis whereas infantile hemangiomas and other vascular tumors are proliferative. Vascular tumors in the current ISSVA classification are subdivided into (a) benign, (b) locally aggressive or borderline, and (c) malignant; each has unique features based upon histology, biology, clinical appearance, behavior, prognosis, and treatment (Table 118-1).
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There are several types of vascular tumors, many of which occur in childhood. These tumors also have confusing nosology,4 with descriptive but imprecise terminology such as strawberry, capillary, and cavernous. The nonspecific term hemangioma should be avoided as a standalone term without a qualifying descriptor (eg, infantile, rapidly involuting congenital, lobular capillary, spindle cell).
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INFANTILE HEMANGIOMAS
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AT-A-GLANCE
Infantile hemangiomas are the most common tumor of infancy.
Infantile hemangiomas in high-risk anatomic sites are likely to require further workup and treatment.
Segmental infantile hemangiomas are associated with greater morbidity than localized infantile hemangiomas.
Kasabach-Merritt syndrome does not occur with infantile hemangiomas.
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Infantile hemangiomas (IHs) are the most common benign tumors of childhood, occurring in approximately 4% to 5% of children.4-7 IHs are distinguished from other vascular tumors and malformations by their unique growth pattern (rapid proliferative phase with subsequent slower involution.) They are more common in girls (2 to 3:1 ratio), in white, non-Hispanic infants,6,8,9 and infants with low birth weight, and affect up to 30% of premature infants,5,10 especially those weighing less than 2500 g....